WO1996007168A1

WO1996007168A1 - Systems and methods for automated toll collection enforcement

Info

Publication number: WO1996007168A1
Application number: PCT/US1995/009156
Authority: WO
Inventors: John J. Hassett
Original assignee: At/Comm Incorporated
Priority date: 1994-09-01
Filing date: 1995-07-21
Publication date: 1996-03-07
Also published as: AU3137695A

Abstract

Automated toll collection systems are provided with systems for detecting vehicles (14) that fail to pay required tolls. In one embodiment of the invention the toll enformecent system includes a vehicle detector (t2) that can detect each of the vehicles approaching a toll plaza (18), and a beacon detector (24) that can detect beacon signals generated by the vehicles (14) approaching the toll plaza (18). The beacon signals can be generated by an in-vehicle component carried by the vehicle. In one aspect, the beacon signals are optically detectable signals which are displayed through the windshield of authorized vehicles approaching the toll plaza (18). The beacon detector (24) can include a camera element which captures images of the approaching vehicles. The beacon detector can analyze the acquired images to determine if any of the approaching vehicles fails to produce a beacon signal. Any vehicle (14) that is approaching the toll plaza (18) and that fails to generate a beacon siganl can represent an unauthorized vehicle. The beacon detector can generate an enforcement signal that will activate an enforcement mechanism to compel the unauthorized vehicle to pay the requisite toll.

Description

SYSTEMS AND METHODS FOR AUTOMATED TOLL COLLECTION ENFORCEMENT

Field of the Invention

The preser.i. invention relates to systems and methods for automated toll collection and more particularly to systems and methods that detect the failure to pay toll fees and that record characteristics of the offending vehicle for enforcement purposes.

Background of the Invention

An increasing number of vehicles are traveling over progressively more congested highways. The collection of tolls by conventional means has had a negative effect upon highway throughput and safety. Congestion and long backups on toll plazas are becoming more common. Such conditions involve a significant economic cost. through lost time, and reduced productivity. Moreover, serious accidents at toll plazas, caused by operator or mechanical failure, have also increased in frequency.

Certain toll authorities have attempted to respond to these problems by providing coin-operated toll collection devices, or by instituting a toll-plate system in which toll-takers visually inspect each incoming vehicle for an appropriate toll plate or sticker. Coin-operated toll collection systems, however, do little to increase throughput, and are susceptible to fraud, through the use of counterfeit coins. Toll-plate systems suffer the same deficiencies, requiring each vehicle to slow sharply while entering the visual inspection area; these systems also rely heavily on toll-taker attentiveness.

In response to the inability of conventional toll collection systems to meet the demands created by increased highway traffic, automatic toll collection systems have been developed and presently exist that can collect tolls from vehicles moving at highway speeds along toll roads.

Typically these systems include an automated toll plaza that has a toll gantry extending across the width of the roadway, a radio frequency toll collection system that broadcasts a toll collection signal to vehicles traveling on the roadway, and transponder units carried by each vehicle on the roadway for detecting the toll collection signal broadcast from the gantry, debiting a toll cash stored in the transponder, and for generating a handshake signal back to the gantry that indicates that the vehicle has paid the assessed toll. This exchange of radio signals takes place within a few tenths of a second while the vehicle speeds along the road and travels under the toll gantry. The clear advantage of these automated toll collection systems is that they relieve the congestion that occurs around the conventional manually operated toll plazas.

However, as can be seen from the above description, an automated toll collection system that allows vehicles to travel through toll plazas at highway speeds must allow each vehicle to have a free path through the toll plaza. Consequently, these automated toll collection systems cannot employ gates, treadles, or other devices that stop each vehicle at the toll plaza until the toll collection system is satisfied that the vehicle has paid the assessed toll. Therefore, although these systems offer tremendous advantages for traffic management, enforcing toll fees is difficult and scofflaws can freely travel along the toll road and pass through the toll collection stations without paying the assessed toll fee.

Enforcement mechanisms have been proposed that place a law enforcement officer at each toll plaza. The law enforcement officer can visually inspect each automobile passing through the toll plaza to identify those vehicles that do not have a transponder unit visibly located behind the windshield of the vehicle. Although this system can work well for detecting vehicles traveling without transponder units it is a costly and labor intensive procedure, it places a high burden on the resources of law enforcement officials, it is difficult to implement at nighttime or during other times of poor visibility, and it is not capable of determining if a vehicle is traveling with a failed transponder unit or an imitation transponder unit.

Additional problems arise for automated toll collection systems that distinguish between the different types of vehicles traveling on the toll road, and assess toll fees based on these categories. For example, an automated toll collection system can be implemented that provides a different type of transponder, with a different toll fee schedule, for different types of vehicles such as motorcycles, cars, light trucks, heavy trucks, and other types of vehicles. Although the inner mechanisms of these transponder units can be different, to compute the toll appropriate for the type of transponder unit and vehicle traveling on the road, the outward appearance of each of these transponder units typically is identical. Therefore, this leaves open the situation where a vehicle, such as a heavy truck, can purchase a transponder unit for a motorcycle and place the transponder unit within the vehicle. The heavy truck can pass through the toll plaza, paying the lesser toll fee, and a law enforcement official would be unable to detect this infraction.

Accordingly, it is an object of the present invention to provide improved systems and methods for detecting vehicles traveling on toll roads that have failed to pay the assessed toll fee. It is another object of the present invention to provide systems and methods for detecting vehicles on toll roads that fail to pay the assessed toll fee for the associated class of vehicle.

It is another object of the present invention to provide systems and methods for detecting toll violations on toll roads that allow vehicles to move across lanes while passing the toll station.

Still another object of the invention to provide improved toll collection methods and apparatus that significantly increase the traffic capacity of roadways.

Another object of the invention is to provide toll collection methods and apparatus that increase the rate of toll collection while enhancing highway safety.

A further object of the invention is to provide such methods and apparatus that are convenient to use and support toll collection by a plurality of toll authorities or authorities at a plurality of widely separated locations.

These and other objects of the invention will be made apparent from the following description of illustrative certain embodiments.

Summary of the Invention

The foregoing objects are attained by the invention, which provides methods and systems for automatically collecting tolls from a vehicle moving at high speed along a roadway.

One aspect of the invention includes at least a first toll facility through which the vehicle can pass for toll collection, and an in-vehicle transponding toll processor having storage for storing a toll-money-available signal representative of a monetary quantity available for debiting in a toll transaction at an upcoming toll facility and a vehicle-specific identifier. Initially, the toll processor is loaded, for example, at a toll facility, with an electronic gross-toll-amount signal representative of an initial toll- money-available value.

A first toll-facility-identification site, corresponding to and remote from a first toll facility collection site, transmits a first toll-facility-identifier signal uniquely representative of (i) the location of the first toll facility and optionally also (ii) a toll schedule corresponding to the roadway. As the moving vehicle approaches the first toll- facility-identification site, the in-vehicle toll processor receives and stores the first toll- facility-identifier signal, and calculates, in response to the first toll-facility- identifier signal, a toll amount to be debited at the first toll facility.

In particular, the in-vehicle toll processor compares the calculated toll amount with the toll-money-available signal stored in the in-vehicle processor, to test whether the monetary quantity represented by the toll-money-available signal is greater than or equal to the calculated toll amount. The in-vehicle toll processor preferably responds to a selected result of this comparison by providing the vehicle operator with a signal, such as a beep, or a beep accompanied by a flashing colored light, representative of permission to utilize the first automated toll facility.

Subsequently, as the vehicle approaches and passes through the first toll facility collection site, the first toll facility collection site transmits a toll-collect signal instructing the in-vehicle toll processor to debit the toll amount from its storage. The in- vehicle toll processor responds by debiting the calculated toll amount from its storage, reducing the value of the toll-money-available signal in accordance with the amount debited. Additionally, the in-vehicle toll processor transmits transaction acknowledgment signal indicating to the toll facility collection site its identification, the calculated toll amount and the account balance.

The in-vehicle toll processor receives the second toll-facility-identifier signal, and if the vehicle did not previously pass through the first toll collection facility, the in-vehicle toll processor overwrites the stored first toll-facility-identifier signal with the second toll-facility-identifier signal.

In another aspect of the invention, precise identification of the position of a vehicle as it passes a toll station is achieved. In one embodiment of the invention, at least one stationary transceiver unit is positioned above one lane of a multi-lane roadway that transmits an identification signal in a known field pattern. A mobile transceiver unit traveling along the multi-lane roadway receives the identification signal and decodes the identity of the stationery transceiver unit and evaluates the strength of the signal. From this information, the mobile transceiver determines its position with respect to the stationery transceiver unit.

In particular, at least one stationery transceiver unit is positioned above one lane of a multi-lane roadway. The transceiver includes a highly directional antenna that transmits a radio-frequency signal. The signal is directed along the roadway and in the direction of oncoming traffic. The directional signal broadcast from the antenna sets up a field pattern within one lane of the multi-lane roadway. By encoding the signal with information that identifies the lane in which the antenna is directed, a radio-frequency field can be set up that uniquely identifies one lane of the roadway.

A vehicle equipped with a transceiver made in accordance with the present invention can determine its lane of travel and its distance from the stationery transceiver by receiving and processing the antenna field pattern. The mobile transceiver, fixed within a vehicle such as an automobile, receives signals generated by the stationery transceivers. The mobile transceiver then decodes these signals and determines from which lane the signal was broadcast. The mobile transceiver then associates with each lane identity a signal strength that can be compared to the known field pattern of the stationery transceiver directional antenna. The mobile transceiver processes the signal strength and signal identity and determines its location relative to the stationery transceiver.

Subsequently, as the vehicle passes the stationery transceiver units, it transmits its vehicle identification number and its lane position so that the stationery transceivers know which vehicle is passing in which lane and can further determine the position of the vehicle relative to the transceiver unit.

In a further aspect of the invention, automated toll collection systems are provided with systems for detecting vehicles that fail to pay required tolls. In one embodiment of the invention, the toll enforcement system includes a vehicle detector that can detect each of the vehicles approaching a toll plaza. The vehicle detector can generate a signature signal for each of the approaching vehicles that uniquely identifies that vehicle. Furthermore, the vehicle detection system can track each vehicle as it approaches the toll plaza, by generating signals which represent the position of each vehicle relative to the toll plaza. The enforcement system further includes a beacon detector that can detect beacon signals generated by the vehicles approaching the toll plaza. These beacon signals can be generated by an in-vehicle-component carried by the vehicle. In one aspect, the beacon signals are optically detectable signals which are displayed through the windshield of authorized vehicles approaching the toll plaza. The beacon detector can include a camera element for detecting optical beacon signals and which captures images of the approaching vehicles. The beacon detector can analyze the acquired images to determine if any of the approaching vehicles fails to produce a beacon signal. Alternatively, the beacon detector can include beam forming antenna for detecting beacon signals, including beacon signals generated in the radio-frequency spectrum. Any vehicle that is approaching the toll plaza and that fails to generate a beacon signal can represent an unauthorized vehicle. The beacon detector can generate an enforcement signal that will activate an enforcement mechanism to compel the unauthorized vehicle to pay the requisite toll. In one preferred embodiment of the invention, the enforcement mechanism includes a recording unit connected in communication with the beacon detector and the vehicle detector, to record certain characteristics of the offending vehicle as it passes through the toll plaza. The recorder unit can include collection elements, such as cameras, that photograph or record video images of the offending vehicle as it passes through the toll plaza. Preferably, the recorded images include an image of the license plate of the offending vehicle. The images can be stored in a database memory that can be reviewed at a later date by a law enforcement official who can issue a citation to the offending vehicle.

In a preferred embodiment of the invention, the beacon signal generated by the in-vehicle component is an infra-red signal generated by a light emitting diode. In alternative embodiments of the invention, the beacon signal can be a near-infra-red signal, an ultra-violet signal, a visible signal, a combination of plural wavelengths, or any other optically detectable energy source.

In a further embodiment of the present invention, a data transmitter is positioned along the roadway and before the toll plaza to generate a signal that can deactivate the beacon generators of vehicles traveling along the toll road. In one embodiment of the present invention, the transmitter continuously broadcasts a black list signal that includes vehicle identification numbers of vehicles that are not authorized to pass through the toll plaza. The in-vehicle component can detect the black list signal and compare the broadcast vehicle numbers with the vehicle identification number stored in the IVC. If the in-vehicle component detects a match between the stored vehicle number and a vehicle number broadcast from the transmitter, the in-vehicle component can deactivate, or disable, the beacon signal generator.

The invention will next be described in connection with certain illustrated embodiments; however, it should be clear to those skilled in the art that various modifications, additions and subtractions can be made without departing from the spirit or scope of the invention as recited in the claims.

Brief Description of the Drawings

For a more complete understanding of the nature and objects of the invention, reference should be made to the following detailed description and the accompanying drawings, in which: FIG. 1 is a schematic block diagram depicting an automatic toll collection system in accordance with the invention, adapted for use on fixed toll roads;

FIG. 2 is a schematic block diagram of another embodiment of the invention, adapted for use on progressive toll roads;

FIG. 2A indicates an alternative embodiment;

FIG. 3 is a schematic block diagram depicting detail of an in-vehicle component (IVC) utilized in the embodiments of FIGS. 1 and 2;

FIG. 4 is a block diagram depicting detail of TO and Tl transmitters constructed in accord with the invention;

FIG. 5 is a block diagram depicting a T2 transmitter subsystem constructed in accord with the invention;

FIG. 6 depicts one enforcement subsystem utilized in the embodiments of FIGS. 1 and 2; and

FIG. 7 depicts RF shielding fields generated in accord with the invention;

FIG. 8 is a block diagram of a Toll Transaction Management (TTM) systems utilized in the embodiments of FIGS. 1 and 2;

FIGS. 9A and 9B depict a simplified form of the COLLECT signal generated by the T2 transmitter, and a simplified form of the acknowledgment signal generated by the IVC in accord with the invention;

FIG. 10 shows a schematic block diagram of a roadway traffic monitoring and management system according to the invention:

FIG 11 is a graphical depiction of the antenna field pattern plotted in polar coordinates;

FIG. 12 is a graphical diagram of one embodiment of the present invention illustrating the pattern of radio field energy established by an antenna; FIG. 13A is a schematic block diagram of a vehicle transponder, particularl) adapted for operation in the system of FIG. 1 1 ;

FIG. 13B is a schematic block diagram of one embodiment of an early warning unit adapted for use in the vehicle transponder illustrated in FIG. 14A.

FIG. 14 is a schematic block diagram in accord with one embodiment of the invention for determining the linear distance from a roadway traffic transceiver; and

FIG. 15 is a flow diagram of the microprocessor code that determines the validity of a lane detection signal;

FIG. 16 is a schematic block diagram depicting an automatic toll collection system having a toll enforcement device in accord with the present invention;

FIG. 17 illustrates from a side perspective an enforcement system constructed in accord with the present invention;

FIG. 18 is a schematic block diagram of an in vehicle transponder component for use with a toll collection system as depicted in FIG. 17.

Description of Illustrated Embodiments

The invention involves a bi-directional module in each vehicle for reception, storage, computation, and transmission of information, wherein the modules communicate with transceivers at a toll station that preferably includes a beacon detector unit that detects beacon signals generated by the module. While all communications can occur while vehicles are traveling at highway speeds, the location of each vehicle is known with precision, allowing effective enforcement against scofflaws and toll offenders.

Fixed Toll Road Operation

FIG. 1 depicts the overall structure and operation of an electronic toll collection system 10 constructed in accord with the invention, for use on fixed toll roads, or on bridges or tunnels. The illustrated embodiment enables automatic collection of toll charges from vehicles moving through a toll facility or plaza at speeds between zero and approximately sixty miles per hour. Vehicles need not halt or slow significantly for toll collection.

For purposes of simplicity, FIG. 1 shows only a single-lane road 12. on which the direction of travel for a given vehicle 14, referred to herein as the

"downstream" direction, is indicated by arrows. Those skilled in the art will appreciate that the invention can be practiced in connection with multi-lane, divided roadways, or in railway networks or other transport systems.

The illustrated embodiment includes two primary components. The first is a communications system having two transmitter modules, referred to as Tl and T2. These transmitters will typically be owned by the toll authority and situated on toll authority property. The second component is an in-vehicle toll processor or in-vehicle component (IVC) 16 purchased or leased by vehicle operators. As described below, the IVC 16 contains a transponder, microprocessor, and memory, for storing, manipulating, and reporting on a quantity representative of money available to the vehicle for debiting in toll transactions. The IVC controls and processes toll-related debit/credit transactions, including extraction of toll charges, by communicating with Tl and T2.

As indicated in FIG. 1 , the Tl transmitter is situated adjacent to the roadway 12, approximately one-quarter to one-half mile upstream from the toll plaza 18, such that vehicles moving at speeds between zero and approximately sixty miles per hour encounter the Tl signal well before encountering the toll plaza. The Tl module radiates an electromagnetic "toll-facility-identifier" signal that identifies the upcoming toll plaza. In the illustrated embodiment, the signal generated by Tl is a radio frequency (RF) signal.

The second transmitter module, T2, is situated at the toll plaza. The T2 module is a transmitter/sensor device that initiates the toll transaction by transmitting an encoded COLLECT signal 20, as described below.

In the embodiment depicted in FIG. 1 , toll transactions occur in the following manner: At some time prior to the vehicle's arrival at the toll collection plaza, a toll authority agent at a toll credit facility 17 loads the IVC with a value representative of an initial toll-money-available quantity purchased by the vehicle operator. The IVC is also loaded with a code representative of the class of vehicle in which the IVC is installed. (This aspect of the invention is further described hereinafter.) The vehicle operator places the IVC in the vehicle and proceeds along the roadway. Approximately one-quarter mile to one-half mile from the toll plaza, the vehicle and IVC pass through a radio field 19 generated by transmitter Tl . The Tl radio signal 19 contains a toll code identifying the upcoming toll collection facility. In one embodiment of the invention, the toll code also includes the toll schedule for the roadway, specifying the toll due for various classes of vehicles. For IVC units used only on fixed toll roadways, the schedule can be stored in the IVC.

Based on the information provided to the IVC by the Tl transmitter, the IVC calculates the appropriate toll due for the class of vehicle in which the IVC is installed. The IVC reads this information and interrogates its memory, to test whether a sufficient toll-money-available balance exists in the account corresponding to the toll authority for the roadway. If the toll-money-available quantity in the appropriate account exceeds the cost of the upcoming toll, the IVC generates a perceptible "PROCEED" message on an associated visual display element, to indicate to the vehicle operator that he or she may proceed through the automated toll facility.

If the cost of the upcoming toll exceeds the toll-money-available quantity for the relevant account, the IVC generates an appropriate alarm message, which can include, for example, an audible alarm and a visual display such as "INSUFFICIENT- MERGE LEFT." The vehicle operator is thereby advised to proceed to a standard toll booth.

Assuming a sufficient toll-money-available balance is indicated in the appropriate tollway authority account, a confirmatory user-perceptible signal is generated and the vehicle and IVC proceed to an electronic toll collection lane.

Referring again to FIG. 1, as the vehicle passes through the toll collection facility at a speed of approximately 0-60 miles per hour, the (T2) transmitter transmits a COLLECT signal 20 that instructs the IVC to debit the calculated toll amount from the toll-money-available quantity stored in its memory. In response, the IVC debits the calculated amount and transmits an acknowledgment signal 22 to the T2 indicating that the IVC has executed an appropriate debit transaction. As further described below, a reader unit 24 at the toll collection facility receives the acknowledgment signal and energizes a green light in an enforcement light array 26.

When the toll transaction is completed, the toll-money-available quantity stored in IVC memory is reduced by an amount corresponding to the toll, and the toll- money-available balance remaining in the account is displayed. The IVC can store different toll-money-available signals corresponding to a plurality of toll authority accounts, in a manner described in greater detail hereinafter. A single IVC is thus operative for toll collection by multiple toll authorities. This feature of the invention is especially advantageous in geographical regions having roads, bridges and tunnels governed by several toll authorities.

While FIG. 1 depicts only one T2 module, governing a single lane, the invention can also be practiced in connection with multiple automated lanes, each governed by a respective one of a plurality of T2 transmitters. In order to reduce the possibility of RF crosswalk between multiple lanes, and to increase longitudinal discrimination between individual vehicles in a single lane, an RF shielding module 28 is provided. The operation and structure of the shielding field module is discussed below.

The illustrated system includes a transmitter control element 30, for directing the T2 transmitter to emit the COLLECT signal when the proximity of a vehicle is detected by a vehicle detector 38, a reader unit 24 for receiving the IVC acknowledgment signals, enforcement lights 26 for indicating vehicle class and identifying any vehicle that proceeds without generating a proper acknowledgment signal, a Toll Transaction Management (TTM) system 32 for recording toll transactions for the toll authority, and cash terminals 17 coupled to the TTM for enabling vehicle operators to purchase prepaid toll-money-available quantities. The structure and function of these elements are described in greater detail hereinafter.

FIG. 1 thus depicts an embodiment of the invention adapted for employment on fixed toll roadways. The invention can also be practiced on progressive toll roadways, in the embodiment depicted in FIG. 2.

Progressive Toll Road Operation

The system 10 illustrated in FIG. 2 is adapted for use on progressive tollways such as turnpikes, where toll values are calculated on the basis of known entry and exit points. On such roads, vehicles enter and exit the roadway via selected on- ramps and exit ramps, selecting a given exit and passing others. Typically, a separate toll facility is located at each exit ramp.

The progressive toll embodiment of the invention utilizes the IVC, Tl, and T2 transmitters discussed above in connection with the fixed toll system. Additionally, as indicated in FIG. 2, another transmitter, referred to herein as a TO transmitter, is located adjacent to each on-ramp 11 to the progressive toll road 12. Each TO transmitter emits an entry-point-identifier signal 42 uniquely identifying the on-ramp to which the TO corresponds. This signal is used to advise the IVC of the vehicle's entry point onto the progressive toll highway.

As the vehicle enters the tollway, the vehicle and IVC pass through the

(TO) radio field that contains the encoded entry-point-identifier signal 42 specifying the entry ramp location or entry ramp number to the IVC. The IVC stores this information in its memory element.

Approximately one-quarter to one-half mile from each exit ramp plaza, the vehicle and IVC approach the Tl transmitter and receive the Tl encoded toll-facility- identifier signal identifying the upcoming exit ramp toll collection facility. The Tl signal also specifies the toll schedule for the roadway. This toll schedule includes distance/cost and vehicle class/cost data.

In response to the Tl signal data, and based on the TO entry-point data stored in the IVC, the IVC calculates the appropriate toll due for the vehicle in which the IVC is installed.

The IVC reads this toll data and interrogates its memory to test whether a sufficient toll-money-available balance exists in the account corresponding to the toll authority for the roadway.

If the cost of the upcoming toll exceeds the toll-money-available quantity for the relevant account, the IVC generates user-perceptible alarm messages, which can include, for example, an audible alarm and a visual display such as "INSUFFICIENT FUNDS ~ MERGE LEFT." The vehicle operator is thereby advised to utilize a standard toll booth if the operator elects to exit the tollway at the upcoming exit ramp.

If the toll-money-available quantity in the appropriate account equals or exceeds the cost of the upcoming toll, the IVC generates a perceptible "PROCEED" message on its display element, to indicate to the vehicle operator that he or she may proceed through the automated toll facility if the operator elects to exit the tollway at the upcoming exit ramp.

Operation at the toll facility then proceeds in a manner similar to that described above in connection with the fixed toll embodiment of the invention. If the operator of the vehicle elects not to exit the tollway at the upcoming exit ramp, and instead chooses to pass the current exit and proceed to a subsequent exit, the vehicle and IVC will encounter at the next exit ramp a subsequent Tl transmitter, corresponding to, and spaced apart from, the subsequent exit ramp toll collection facility. In response to receiving this new Tl signal, the IVC stores the new Tl data in memon', overwriting the old Tl data. The TO entry-point information is retained, however, and the IVC executes a new toll calculation and toll-money-available test, based on the TO data and new Tl information. This cycle is repeated for each automated exit facility that the vehicle operator elects to pass. The TO entry-point information is erased from memory after receipt of a T2 TOLL-COLLECT signal at a toll collection facility, or upon receipt of new TO data, which occurs when the vehicle re-enters a progressive toll road.

In the illustrated embodiments, the Tl transmitter is located approximately one-quarter to one mile from the T2 transmitter to avoid improper detection of Tl signals by IVC units approaching the toll facility from the opposite direction. Additionally, to assure that a Tl does not improperly reset an IVC approaching from the opposite direction before the IVC passes through its respective T2, the Tl transmitter can be angled towards oncoming traffic and away from the opposite direction of traffic.

In addition to the foregoing specific embodiments of an automated toll collection system, the invention contemplates systems wherein the distribution of processing and accounting data between the IVC and the T2 / central system contains further, or dynamically changing information, yet allows transactions to be effectively completed in short times and with minimal possibility of system abuse or data error.

In one such system, indicated in Figure 2 A, the schedule of vehicle tolls described above is transmitted not by the exit identifying transmitter Tl, but by each entrance transmitter TO. When toll schedule information is provided to the IVC in this manner, each transmitter TO need not transmit a full matrix of toll amounts for all entries and exits, but needs only to transmit the toll schedule for vehicles entering the particular fixed entry at which that TO is located. Thus, for example, where a progressive toll schedule depends on entry point, exit point and vehicle class, then rather than a three- dimensional toll schedule matrix, TO transmits the entry identifier and a two-dimensional toll matrix arranged by vehicle class and exit numbers. The IVC then receives and stores so much of the table as is relevant to it. It is contemplated that each IVC will be issued for a fixed vehicle class (e.g., 2-axle private vehicle, 3-axle commercial vehicle under 10 tons weight, etc.), so as the vehicle passes an entry transmitter TO it receives the transmitted schedule and stores a simple one-line table of tolls corresponding to the toll at each exit for vehicles of its own vehicle class, arranged by exit number.

Thus, as the vehicle enters the roadway it acquires all information it needs for subsequent toll payment. In particular, the step of checking that its account maintains an adequate balance may also be done at any time after this point, rather than in the environs of Tl at its intended exit point, where the traffic and the RF signal environment are each more congested and likely to cause error or delay.

The IVC

FIG. 3 depicts detail of the IVC 16. The IVC includes a processing element 50, an associated EPROM 52 for storing control software 53, a CMOS RAM element 54 for storing toll-money-available quantities and other data, control firmware 55, an RF transmitter 56 and associated antenna module 58, an RF receiver 60 and associated antenna module 62, user interface elements 66, 68, 70, a bi-directional communications port 64, and power supply elements.

The processing element 50 can be an 8086 or other microprocessor capable of executing the calculations necessary to determine toll amounts, based on a toll schedule received from Tl transmitters. The microprocessor also controls decoding and inteφretation of encoded signals, in a manner described in greater detail hereinafter. The RAM element 54 preferably provides sufficient non-volatile memory to store toll data for a large number of toll authority accounts.

The IVC antennas 58, 62 can be incoφorated into the IVC, or a receptacle can be provided to attach to a conventional window-mounted antenna, similar to those employed in connection with cellular telephone devices.

The user interface elements preferably include user-operable keys 66, LCD or LED display units 68, and an audio alarm module 70. The display and audio alarm elements provide visual or audible alarm signals when necessary, while the keys and display elements enable the vehicle operator to obtain information relating to toll- money-available quantities for each toll authority account stored in the IVC RAM. The display and user interface keys, in combination with conventional EPROM-stored software routines for controlling the microprocessor, enable the user to view the balances of each account stored in the IVC RAM. In one embodiment, the user interface includes an alphanumeric display having two lines of 10 characters each. The bi-directional communications port 64 enables other microprocessors, including toll authority data processors, to write data into, and read data from, the IVC RAM. These read/write functions, which include purchase of gross toll quantities, diagnostic operations, and report generation, are discussed in greater detail hereinafter.

The power supply elements preferably include a compact, user-replaceable long-life battery 74, such as a lithium power cell. These elements can also include an on/off switch incoφorating a battery check position.

The IVC components depicted in FIG. 3 are conventional in design and construction, and the IVC can be constructed in accord with known transponder and microprocessor control principles. The illustrated IVC transponder/processor can be housed in a compact, portable enclosure adapted for removable attachment to a dashboard surface or other convenient location within the vehicle.

The combination of components depicted in FIG. 3 enables the IVC to process fixed toll and progressive toll transactions. Additionally, the IVC can store and process different toll values for various toll authorities, toll facilities, and toll booths, so that a single IVC can accommodate multiple toll authorities and the expanded progressive toll tables required for multiple vehicle classes.

In particular, the IVC receives, decodes, and stores the Tl transmitter signal, inteφrets the stored signal, calculates the required toll amount based upon the stored signal, store the calculated toll amount, and debits the calculated amount at the toll facility in response to a COLLECT signal from the T2 transmitter. The IVC debits the calculated toll quantity from the appropriate account and transmits an acknowledgment signal that includes a vehicle-class message and confirmation of the debit operation.

As discussed in further detail below, the acknowledgment signal takes the form of an encoded logical response to the COLLECT signal from the T2 transmitter. The acknowledgment is dependent upon the content of the COLLECT message.

Following transmission of the acknowledgment, the IVC remains inactive until it passes through another Tl field. The IVC thus consumes power intermittently, and only when required for toll data processing. This feature reduces average power demands, and significantly extends battery life. IVC Data Fields

In one practice of the invention, toll account information stored in the IVC includes individual toll road files having data fields with the following information:

Field Size

Start File 2 bits

Toll Facility Name 10 bits

Previous Balance 6 bits

Amount Debited 6 bits

Amount Credited 6 bits

Current Balance 6 bits

End File 2 bits

Those skilled in the art will appreciate that the invention can be practiced in connection with other data field parameters.

Each data file can be manipulated and edited as required for individual transactions between the IVC and the toll collecting T2 module, or between the IVC and the toll authority data processing system, as described in greater detail hereinafter.

IVC Operational States

In accord with one embodiment of the invention, the IVC unit can utilize the following operational states:

State Number Description

0.0 IVC off.

1.0 IVC switched on.

1.1 Upon switching on, lack of response signifies that the system is inoperable.

1.2 Upon switching on, system comes up, executes battery check, displays "OK" message, sounds beep. 1.2.1 Upon switching on, system comes up, executes battery check, detects low battery condition, displays "LOW BATTERY" message, sounds beep.

1.2.2 IVC enters hibernation — a state in which little or no power is consumed, and the IVC waits to sense a signal.

1.2.3 IVC detects a transmission, exits hibernation and prepares to read encoded message.

1.2.3.1 Attempts to read message, fails three times, displays "error" and "proceed". sounds beep.

1.2.3.2 Reads message correctly, verifies correct read.

1.2.3.2.1 Checks whether message is TO, Tl,

T2.

1.2.3.2.1.1 Determines that message is TO.

1.2.3.2.1.1.1 Sounds beep, deletes from memory all current travel data" ~ i.e., current memory for current trip.

1.2.3.2.1.1.2 Saves to "travel data" record, enters hibernation

1.2.3.2.1.2 Determines that message is a Tl record, will not read another Tl record for 2 minutes.

1.2.3.2.1.2.1 Determine whether Tl message is fixed or progressive. 1.2.3.2.1.2.1.1 Determines that Tl record is progressive

1.2.3.2.1.2.1.1.1 Looks for TO in "travel data" memory, not found.

1.2.3.2.1.2.1.1.1.2 Sounds beep, displays "error" and

"proceed".

1.2.3.2.1.2.1.1.3 Enters hibernation.

1.2.3.2.1.2.1.1.2 Looks for TO in "travel data", finds

TO record

1.2.3.2.1.2.1.1.2.1 Sounds beep, displays "OK", calculates toll due at next T2 based on comparison between TO record and current record, deletes previous Tl record if any in "travel data".

1.2.3.2.1.2.1.1.2.2 Enters hibernation.

1.2.3.2.1.2.1.2 Determines Tl record is of fixed toll type.

1.2.3.2.1.2.1.2.1 Deletes previous Tl record (if any in "travel data").

1.2.3.2.1.2.1.2.2 Sounds beep, displays "OK", calculates toll.

1.2.3.2.1.2.1.2.3 Goes into hibernation.

1.2.3.2.1.3 Determines the message is a T2 record.

1.2.3.2.1.3.1 Returns acknowledgment encoded with vehicle type, deletes toll amount from specified account. 1.2.3.2.1.3.2 Sounds beep, displays "OK", "Thank

You".

1.2.3.2.1.3.3 Clears all "travel data".

1.2.3.2.1.3.4 Enters hibernation

Default Logic:

If an IVC having no "Travel Data" in memory receives a T2, it reads the default toll from T2 record and deletes the default amount from the appropriate account.

IVC l oll Calculation Logic

Fixed Tolls: The IVC passes through a fixed-toll Tl field and receives an encoded Tl record indicating a fixed toll. The IVC then calculates the toll due at the next T2 site, based on the fixed rate found in the toll schedule field. If the IVC passes through another Tl prior to encountering a T2 field, the IVC deletes the old Tl record and replaces it with the new Tl record.

Progressive Tolls: The IVC passes through a TO field and the encoded TO record is stored future processing. This record includes the following:

1. Start message 2 bits

2. Toll facility identifier 6 bits

3. Direction identifier 2 V ^:ts

4. TO identifier 2 .is

5. End message 2 its

Upon receiving a TO message the IVC deletes all "Travel Data" in memory.

As the IVC passes through a Tl field, it receives an encoded record indicating a progressive toll, as follows:

1. Start message 2 bits

2. Toll facility identifier 6 bits

3. Direction identifier 2 bits

4. Tl identifier 2 bits 5. Toll type (progressive or fixed) 2 bits

6. Toll schedule 256 bits

7. End message 2 bits

Having received the TO and Tl records, the IVC calculates the toll due at the next T2 it encounters. If the IVC passes through another Tl field before it encounters a T2, the IVC deletes the previous Tl record, replaces it with the new Tl record, and recalculates the toll due.

Upon passing through to a T2 the IVC debits the appropriate toll from the specified IVC toll authority account.

The entire T2 record includes the following:

1. Start message 2 bits

2. T2 identifier (simply states that the transmitter is a T2) 2 bits

3. Toll authority /booth identifier 6 bits

4. Direction identifier 2 bits 5. Default toll amount 8 bits

6. End message 2 bits

These TO and Tl records contain all data required for calculating a progressive toll. The direction identifier can be use in error detecting calculations.

The 256 bit toll schedule field in the progressive-toll Tl record is a matrix of toll values based on entry points (A-C in this example) and exit points (A-C) specified in the TO and Tl records, respectively:

A B C

A 0 $ $ B $ 0 $ C $ $ 0

TO. Tl Transmitters

FIG. 4 depicts the structure of entry ramp transmitters TO and toll-facility- identifier transmitters Tl constructed in accordance with the invention. Those skilled in the art will appreciate that while the illustrated TO and Tl transmitters utilize radio frequency signal generating elements, the invention can also be practiced in connection with transponder components utilizing infra-red (IR) or other radiant electromagnetic energy wavelengths.

As discussed above, the TO transmitters and Tl transmitters repeatedly emit an encoded signal that provides the IVC transponder elements with data required for toll calculation and collection.

The TO toll-facility-identifier signal field is encoded with the following record:

1. Start message flag.

2. Toll identifier (identifies toll facility)

3. Direction identifier

4. TO identifier (not a number, simply identifies signal source as a TO)

5. End message flag.

The Tl message is encoded with the following record:

1. Start message

2. Toll identifier (identifies toll facility)

3. Direction (A or B)

4. Toll schedule

5. Tl identifier (not a number, simply identifies signal source as a Tl) 6. Toll type (progressive or fixed)

7. End message

The toll schedule identifies tolls and their breakdown by vehicle type. The Tl signal is incrementally receivable, in that the IVC checks for the required data among the received messages and stores only the message it requires.

The START and END message bits are significant in assuring that individual IVC units read only complete messages, and do not attempt to read a message already in progress. Each of the illustrated transmitter units TO, Tl includes a conventional RF transmitter 82 and antenna element 84, microprocessor and associated erasable programmable read-only memory (EPROM) 86, and power supply elements 88. The EPROM stores software for control and operation of the transmitters. These components are conventional in design and materials, and the transmitters can be constructed in accordance with known engineering practice. The complete TO and Tl assemblies are preferably enclosed in a rugged weatheφroof housing 90, to withstand the ranges of temperature, humidity, and ultraviolet radiation typical of the roadway environment. The Tl transmitter can be activated by an infra-red or optical vehicle detector, so that the Tl transmitter emits signals only when a vehicle is in proximity to the transmitter.

T2 Transmitter

FIG. 5 depicts a toll-collect transmitter T2 in accord with the invention, for transmitting a TOLL-COLLECT signal instructing the IVC to debit the calculated toll amount. In one embodiment of the invention, the TOLL-COLLECT signal is a digital signal containing four bytes of data.

The T2 transmitter is preferably enclosed in weatheφroof housing 92, and includes a conventional RF transmitter module 94 and associated antenna elements 96, a microprocessor, an EPROM for storing control software 98, and power supply elements 100. While the illustrated T2 transmitter includes radio frequency signal generating elements, the invention can also be practiced in connection with transponder components utilizing infra-red (IR) or other radiant electromagnetic energy wavelengths.

The T2 signal is encoded with the following information:

1. Start message flag. 2. T2 identifier (not a number, simply states it is a T2).

3. Toll identifier (includes toll authority and toll booth)

4. Direction identifier 5. Default toll amount — the amount debited if the TO entry-point-identifier is lost or otherwise not present. 6. End message flag. Toll Facility Hardware

In the embodiment depicted in FIGS. 1 and 5, the T2 transmitter is electrically connected to a transmitter control unit (TCU) 30 and a vehicle detector 38. The vehicle detector can be, for example, a photoelectric cell, located within ten to fifteen feet of the T2 transmitter, for optically sensing the presence of a vehicle and generating a VEHICLE PRESENT signal. When the VEHICLE PRESENT signal is relayed to the TCU, the TCU directs the T2 transmitter to transmit the COLLECT message. Thus, the T2 transmitter for a given lane emits a COLLECT signal only when a "target" vehicle is present in the lane, as indicated by the VEHICLE PRESENT signal.

The transmitter control unit is also interconnected with an acknowledgment signal reader unit 24. The reader unit 24, which utilizes conventional RF receiver elements, receives acknowledgment signals — and the vehicle-class identifiers contained therein ~ from each vehicle's IVC, to confirm that a toll debit transaction has been completed. The reader unit can be mounted on the leading edge of the toll facility canopy, angled downward toward oncoming traffic. Multiple reader units covering one direction of traffic at a single toll barrier can be connected to a reader control unit (RCU) that executes diagnostics, records activity in each lane, and forwards records of the activity to the TTM for further processing.

Each time the reader unit receives an acknowledgment signal, the reader unit can transmit the vehicle identifier to the enforcement subsystem depicted in FIG. 6.

The illustrated enforcement subsystem 100 is provided to reduce the possibility of toll evasion. More particularly, in automated toll collection systems utilizing a conventional enabling device such as a magnetic card, tolls can be evaded by utilizing an enabling device designated for a low-toll vehicle class, such as an automobile, in a truck or other high-toll vehicle. The enforcement subsystem 100 addresses this problem and can be a stand alone system or a component of the system illustrated in FIGS. 16 and 17 and described in greater detail hereinafter. The subsystem shown in FIG. 6 governs one automated lane. It includes a vertical array often indicator lights 1 12 housed within a weatheφroof, substantially cylindrical enclosure; a switch unit 1 14, a processor 116, a communications link 1 18, a power supply 120, and an alarm 122. Each indicator light in the light array represents a different class of vehicle — bus, car, truck, or other. The microprocessor 116 controls the switch 114 to energize a selected indicator light, in response to signals from the reader unit 24 for the lane. Signals generated by reader unit 24 are relayed to the processor 116 via communications link 118. Each time the reader unit 24 receives an acknowledgment signal and vehicle-class identifier from an IVC in the lane, the reader transmits the vehicle-class identifier to the communications link, processor, switch, and light column, thereby causing a single selected indicator light to be energized. The selected light is representative of the vehicle class specified by the IVC in the vehicle currently passing through the corresponding lane of the toll facility. Enforcement personnel can then monitor the light column for each automated lane to confirm proper correspondence between visually observed vehicle class and vehicle class indicated by each IVC. Lack of proper correspondence indicates that the IVC in the current vehicle is incorrectly initialized for the class of vehicle in which the IVC is installed.

Moreover, if the vehicle detector for a given lane detects a vehicle, but the reader does not receive a proper acknowledgment signal within a predetermined interval of time, the enforcement processor activates the alarm module. The alarm module can include audible and visible alarm elements such as buzzers and strobe lamps.

RF Isolation

When the invention is practiced in a multiple-lane embodiment, the possibility exists that an IVC or reader unit operating in one lane will inadvertently detect signals generated by transmitters operating in adjacent lanes. The resulting confusion could frustrate system users or permit toll evaders to exploit the automated system. Consider, for example, first and second vehicles and respective IVC units approaching a multi-lane automated toll facility in adjacent first and second lanes, as depicted in FIG. 7. For piuposes of this example, the second vehicle is behind the first. When the first vehicle enters the toll collection zone in the first lane, the T2 transmitter for the first lane transmits a TOLL COLLECT signal. In the absence of appropriate isolation, the second IVC, in the second lane, may receive the COLLECT signal intended for the first vehicle, and transmit an acknowledgment before reaching the second lane toll collection zone. The second vehicle's IVC would subsequently fail to generate the appropriate acknowledgment signal when it reaches the second lane collection zone.

Conversely, without proper isolation, the acknowledgment generated by the first IVC in the first lane may enable a toll evader in the second lane to pass through the second lane toll collection zone without generating a proper acknowledgment, and without triggering an alarm. Thus, certain measures must be employed to reduce the possibility of RF crosswalk between multiple lanes, and to increase longitudinal discrimination between individual vehicles in a single lane.

To permit the reader unit to discriminate between an acknowledgment from a target vehicle IVC and "false" acknowledgments from adjacent vehicles or other sources, the control unit (FIG. 5) prevents the reader unit from detecting acknowledgment signals until the vehicle detector generates a VEHICLE-PRESENT signal indicating physical proximity of a vehicle in the lane.

Additionally, each IVC is programmed to generate its acknowledgment signal within a predetermined number of milliseconds after the T2 transmitter emits the COLLECT signal, and the corresponding reader unit checks for the acknowledgment only during this time window. Enabling the reader unit only when a VEHICLE- PRESENT signal is generated, and using a limited time window for acknowledgment transmission and detection, provides a temporal distribution of acknowledgment signals, thereby reducing the probability that a reader unit for a first lane will detect an acknowledgment from an IVC in an adjacent second lane.

Isolation can also be provided by controlling the transmission time of

TOLL-COLLECT signals transmitted from adjacent lanes such that transmission of TOLL-COLLECT signals and subsequent detection of acknowledgment signals occurs serially, in only one vehicle lane at a time.

Another approach involves enhancement of RF isolation by configuring the

T2 module to generate dual RF fields, as depicted in FIG. 7. One field 130, directed at the intended incoming target vehicle, carries a valid encoded TOLL-COLLECT message. A second field 132, directed at vehicles behind and on either side of the target vehicle, effectively isolates nearby vehicles from the COLLECT message, so that only the target vehicle, which is in close proximity to the T2 transmitter and the reader unit, can receive the T2 TOLL-COLLECT message and generate an acknowledgment. The continuously repeating shielding field signal 132 is not encoded, but in one embodiment of the invention is used to initialize incoming IVC units by incoφorating values instructing the IVC units to prepare to receive a valid, encoded COLLECT signal.

RF shielding elements in accord with the invention, including transmitters 134, antennas 136, and shielding fields 132, are depicted in FIG. 7. The illustrated embodiment utilizes multiple shielding field transmitters 134 having antennas 136 oriented at selected angles to generate overlapping radio fields. This configuration isolates, or shields, a selected "VALID" region in which a T2 TOLL-COLLECT signal or other "VALID" transmission can be received. The shielding transmitters 134 utilize at least two antennas 136. These emitters continuously transmit a time-invariant RF signal that is not encoded. The shielding signal is thus a NO-OP or NO-COLLECT signal that IVC units do not recognize as an instruction to execute a debit operation.

As indicated in FIG. 7, the shielding field RF transmitters 134 and associated antennas 136 are arranged to provide fields 132 having overlapping lobes. Within the shielding field overlap regions, the average amplitude of the shielding signal is higher than that of the T2 COLLECT signal, effectively "blanking out" the COLLECT signal. This configuration provides RF isolation between vehicles in adjacent lanes.

Operation of the shielding elements exploits the fact that the IVC will recognize a COLLECT message only in those regions where sufficient "VALID" signal amplitude is present — i.e., in the "VALID" regions where shielding field lobes do not overlap.

The shielding field antennas 136 can be mounted in selected locations on the toll facility canopy 140, and each antenna can be rotated to selected angular orientations with respect to other antennas in the subsystem, to optimize RF isolation between vehicles and lanes. Preferably, a number of shielding field antennas 136 are located on the leading edge 141 of the toll facility canopy 140, oriented generally toward on-coming traffic, and angled approximately 45 degrees downward from the horizontal plane. Shielding signals of either a single frequency or multiple frequencies can be generated by one or more shielding field transmitters 134.

Isolation between multiple vehicles in a given lane, and isolation from T2 signals from adjacent lanes, is enhanced by utilizing directional antennas in the T2 transmitters, to focus the emitted T2 radio field downward onto oncoming vehicles.

In operation, when the IVC approaches the toll plaza, having already calculated the appropriate toll, the IVC encounters the shielding field, and responds by preparing to receive the encoded "valid" T2 field. The T2 "valid" transmitter, which can be mounted on the toll collection facility canopy approximately midway between the leading and trailing edges 141, 143 of the canopy 140, transmits its TOLL-COLLECT instruction when triggered by the vehicle detector. The IVC debits the toll amount and responds within a predetermined time interval by transmitting a message simply confirming the debit transaction and identifying the vehicle type. In one embodiment of the invention, this acknowledgment signal is a digital signal containing four bytes of digital data.

The RF shielding system can also be used in conjunction with TO on-ramp transmitters, by transmitting a non-encoded second field that shields vehicles traveling on the progressive toll roadway from the TO on-ramp signal.

The illustrated shielding field configuration can also be employed for position detection. In particular, when a signal having a selected frequency is transmitted at different amplitudes from each of the antennas, the relative position of a receiver with respect to the antennas can be determined on the basis of amplitude variations in the received signal as the receiver passes through the overlapping shielding fields. When signals of different frequencies or encoded variations of a single frequency are transmitted from each of the antennas, the relative position of a receiver with respect to the antennas can be determined from differences between received signals as the receiver passes through the overlapping shielding fields.

Toll Transaction Management

In order for an automated toll system to gain wide acceptance, it should provide information and records for accurate accounting of traffic activity and toll transactions at each toll booth and toll facility. The system should also expedite the toll purchase process.

These advantages are provided in one practice of the invention by the Toll

Transaction Management (TTM) subsystem 32 depicted in FIG. 8, which monitors toll collection, enables toll purchase and IVC loading, and generates reports on toll purchase, toll collection, and traffic activity.

The TTM subsystem 32 maintains records of all cash transactions — i.e., toll amount purchases ~ and automated toll debit transactions. These records are maintained and formatted for periodic down-loading to the toll authority central computer. The TTM can also execute diagnostic tests on each IVC as required, and verify the status of the toll accounts in each IVC, as described in greater detail hereinafter.

The TTM subsystem includes a central processor 140, cash terminals 17 in communication with the central processor 140, and a communications link 37 for bi¬ directional data communications with a toll authority central computer 136. The subsystem can also include a data memory and storage module 143 having conventional RAM, magnetic, optical or other digital data memory and storage elements.

The TTM central processor 140 can be a conventional microcomputer or minicomputer, depending upon the size and data-handling requirements of the automated toll system. The central processor is interconnected with the reader units 24 in each automated lane, to gather toll collection data including vehicle-class-identifiers. transaction time, and lane-by-lane traffic activity information. Where required, remote communication between the reader units and TTM central processor can be provided by modems or other data communications devices.

The cash terminals 17 include a conventional display 146, keyboard 148, and printer 150. The terminals also include an RS-232 or other conventional communications port 152 adapted for connection to a similar port 64 on each IVC unit (See FIG. 3). Using the communications port 152, the cash terminals 17 enable vehicle operators to credit their IVC accounts -- i.e., load selected toll-money- available quantities — by prepaying selected toll amounts.

When a motorist wishes to prepay tolls and load the IVC, the motorist proceeds to a local toll facility and gives the IVC to a toll collection agent with cash or a credit card authorization equal to the toll amount the motorist wishes to prepay. The toll collection agent connects the IVC communications port 64 to the cash terminal communications port 152, and enters into the cash terminal the monetary amount to be stored in the IVC memory for a specified toll authority account.

The cash terminal 17 transmits a signal to the IVC 16, indicating a credit for the specified monetary amount to the selected account in the IVC. The cash terminal also prints a receipt verifying the credit to the account. This receipt can specify all toll transactions involving the IVC since the previous cash transaction. The cash terminal 17 then communicates with the Toll Transaction Management (TTM) central processor 140 to confirm the cash transaction. This information is retained in the memory 143 of the TTM for further processing, storage, and communications with the toll agency central computer.

In addition to toll purchases and other cash transactions, the cash terminal

17 can also interrogate individual IVC units 16 to produce printed diagnostic reports or travel data reports. As indicated in FIG. 8, the TTM central processor 140 is connected to each reader unit 24 in the toll facility. When a reader unit 24 receives an acknowledgment and vehicle-class identifier from an IVC, the reader unit 24 relays the vehicle-class identifier to TTM central processor 140 for formatting, further processing, and storage. The formatted record generated by the TTM for each debit transaction is referred to as a Toll Transaction Record.

In addition to Toll Transaction Records, the TTM subsystem configuration depicted in FIG. 8 is capable of generating various records for use by each toll authority. While the number and type of such records will vary, depending upon toll authority requirements, the TTM subsystem can generate Cash Transaction Records, Traffic Records, and Cash Summary Records. The Cash Transaction Record is generated by the TTM, as described above, each time a motorist credits his or her IVC accounts by prepayment of a selected toll amount.

The TTM generates Traffic Records by summarizing relevant data from each incoming Toll Transaction Record. The Traffic Record is then relayed to the Toll Authority's central computer. The Cash Summary Record is generated by the TTM by processing all incoming Cash Transaction Records. The Cash Summary Record is also transmitted to the Toll Authority's central computer. Examples of data fields for each of these records is set forth below.

Because each of these records is intended for ultimate use by different toll authority computers, a standard data format should be utilized for communications with external toll authority processors. Current research indicates that most toll authority computers can read and write ASCII flat files. Thus, in one practice of the invention, the TTM generates files having an ASCII format, enabling standardized output to toll authority computers.

The TTM functions of creating and sorting records based on cash transactions, debit transactions, and traffic activity in each lane, can be provided by utilizing a commercially available database program such as Oracle or Dbase III. Traffic and financial transaction records can be stored, tracked and displayed on the TTM cash terminal display units 146.

In addition, a plurality of TTM subsystems can be distributed along a progressive toll road, with conventional network communications between the TTM subsystems and a mainframe computer at the toll authority headquarters. TTM Data Fields

Each of the TTM Records described above contains selected information relating to toll transactions. Data fields utilized in one practice of the invention are set forth below, by way of example. Those skilled in the art will recognize that the invention can be practiced with data fields other than those set forth below. In each case, data can be transferred to the TTM on a real-time basis as fixed format ASCII records. Each record is terminated by a carriage return/line feed sequence and commences with a "record type" indicator. Whenever a date is required, fields can be date and time stamped in a year-month-day-hour-minute-second format.

TOLL COLLECT DATA FIELDS

FIELD SIZE DEFINITION

record type 2 identifies record type

barrier/lane number 8 4 digits identify barrier number 4 digits identify lane number

IVC serial number 8 identifies IVC unit

amount credited 6 amount purchased 9999.99

current balance 6 current balance 9999.99

end record hard run ends record

TOLL PURCHASE/CASH TRANSACTION DATA FIELDS

FIELD SIZE DEFINITION

record type 2 identifies record type

IVC serial number 8 identifies IVC unit

amount credited 6 amount purchased 9999.99

current balance 6 current balance 9999.99

end record hard rtrn ends record

TRAFFIC RECORD DATA FIELD

FIELD SIZE DEFINITION

record type 2 identifies record type

from date/time stamp 14 record covers from - to

current date/time stamp 14 record covers from - to

barrier/lane number 8 4 digits identify barrier number 4 digits identify vehicle type

vehicle type 4 4 digits identify vehicle type

vehicles through 6 6 digits identify number of vehicles through lane (8 vehicle types, repeats based on number of lanes in system)

end record hard rtrn ends record

CASH SUMMARY DATA FIELD

FIELD SIZE DEFINITION

record type 2 identifies record type

from date/time stamp 14 record covers from - to

current date/time stamp 14 record covers from - to

Terminal num. 4 identifies cash terminal

total cash in 6 total cash in

(repeats last two fields for every cash terminal in system)

end record hard rtrn ends record Signal Encoding

FIGS. 9A and 9B depict COLLECT and acknowledgment signals encoded in accordance with one practice of the invention. In accord with the encoding process, referred to herein as Digital Time Segment Modulation (DTSM), the carrier signal is present at substantial' all times during the transmitter ON state, with brief intervals or gaps 160-163 inserted between digital time segments 164-167. The temporal position of each gap, which defines the length of each digital time segment, is a quantity representative of digital data. In particular, as depicted in FIG. 9, the position of each gap defines bit cells indicative of encoded information.

In the illustrated embodiment, the T2 transmitter emits a carrier signal at 915 MHz, and the acknowledgment signal is transmitted at 46 MHz. Those skilled in the art will appreciate, however, that the DTSM method can be utilized to encode information in electromagnetic signals of arbitrary wavelength or frequency.

As depicted in FIG. 9A, a typical transmitted signal includes a RECEIVER- ADJUST portion 170 during which the receiver adjusts to transmitted signal amplitude; a SYNC or synchronization portion 172 enabling synchronism between receiver and transmitted signal; and a MESSAGE portion 174. The message portion can contain a MESSAGE ASSURANCE portion 176, which includes at least one parity bit or checksum bit, for checking the accuracy of the message in accordance with conventional error checking practice.

The communications event typically includes the following operations:

1. The controller module for the toll facility (FIGS. 1, 2, and 6) receives a VEHICLE-PRESENT signal from the vehicle detector, indicating the presence of a vehicle in the corresponding lane.

2. The controller module for the toll facility activates the T2 transmitter.

3. The T2 transmitter emits an RF TOLL-COLLECT signal encoded in the manner described above and depicted in FIG. 9A.

4. The IVC receives the TOLL-COLLECT signal, debits the appropriate account, and transmits an acknowledgment signal (FIG. 9B) encoded in a similar manner, with gaps 180, 181 inserted between digital time segments 182, 183. The acknowledgment signal can be frequency modulated or amplitude modulated. 5. The toll facility receives the acknowledgment signal and energizes an appropriate signal light in the enforcement light column (FIG. 6).

The DTSM encoding system provides significant advantages over conventional phase, amplitude, or frequency modulation encoding. The carrier signal is present at substantially all times during the transmitter ON state, resulting in high average signal power, and enabling the use of a simple, moderate-sensitivity, low-cost receiver in the IVC to acquire the peak incoming signal. Additionally, the encoding provides a signal in which the data portion has a fixed, known location. The encoding also provides the receiver an extended opportunity to acquire the signal before transmission of the data portion. Moreover, the encoded signal is readily decoded, using conventional digital techniques.

In one embodiment of the invention, the starting position of the acknowledgment message is varied, based upon the time at which TOLL-COLLECT signal is transmitted, as well as upon the contents of the COLLECT signal. Additionally, to reduce the potential for unauthorized recording and reproduction of the acknowledgment signal, the TOLL-COLLECT message is not a fixed message. It is selected from a set of TOLL-COLLECT messages, each of which is recognized by the IVC as a TOLL-COLLECT message. Because the COLLECT message varies over time, and the acknowledgment signal depends upon the time and content of the COLLECT message, the required acknowledgment must also vary over time, so that a previously recorded acknowledgment is unlikely to be valid at a subsequent time.

The encoding system can also insert ancillary machine readable information and user-readable information, including spoken road condition reports for motorists or encoded data for on-board map display devices.

FIG. 10 shows a block diagram of a multi-lane vehicle location system 210 according to the invention. The illustrated embodiment 210 enables vehicle position to be determined and transferred from vehicle transponders, located in host vehicles 212-216, to the lane transmitter units 218-222, as the vehicles 212-216 travel along the roadway 224.

For simplicity, FIG. 10 depicts a three-lane road 224 on which the direction of travel for a given host vehicle, referred to herein as the "downstream" direction, is indicated by arrows. Those skilled in the art will appreciate that the invention can be practiced in connection with roadways having additional lanes, including multi-lane divided highways, bridges and tunnels. As one skilled in the art will appreciate the invention can also be practiced in connection with numerous other transport systems, such as railways, and waterways.

The illustrated embodiment includes two primary components; the vehicle transponders 228, and the lane stationary transceivers 218-222. As discussed in further detail below, a vehicle transponder 228, according to a preferred embodiment, is carried by a host vehicle and includes a radio frequency transmitter and receiver, a central processing unit, an early warning signal detection unit, a signal strength detection unit, a signal decoding unit, and a user interface. The preferred embodiment of the roadway stationary transceiver includes a transmitter unit and a directional antenna having a known antenna pattern directed at the lane below the transmitter unit.

The vehicle transponder 228 receives signals from the lane transmitter units 218-222 and processes these signals to determine which lane stationary transmitter unit sent a particular signal. The transponder 228 may also process the signals to determine the relative strengths of the signals received from the various lane transmitting units. By comparing the measured and strengths of the received signals and comparing this information to known antenna field strength patterns, the transponders can determine their lane position and accordingly the vehicle position relative to the lane transmitting units.

In the embodiment of the present invention illustrated in FIGURE 10, the lane transmitting units 218-222 are positioned across the multi-lane roadway so that one transmitting unit is positioned above each lane. As further indicated by FIGURE 10, each of transceivers unit 218 through 222 radiates a lane identification signal that establishes an antenna field pattern 226 in the direction of on-coming traffic. The lane identification signal is encoded with lane identification information so that a single field pattern is associated with a particular lane. In the illustrated embodiment, the signal generated by transceivers units 218-222 is a radio-frequency (RF) signal.

FIGURE 11 illustrates in more detail the antenna pattern radiated from the transmitting units of transceivers 218-222. In the example illustrated in FIGURE 11, the field pattern is established by a phased array radar system with parasitic directors transmitting at 904.5 Mhz, but it should be apparent that any similar transmitting device known in the art could be used. More specifically, the antenna field pattern was generated by a slotted waveguide array with longitudinal polarization in the direction of travel and beam shaping. The phased array antenna transmits the majority of its radiated energy within the main lobe 240. As is known in the art, the side lobes 242 are minimized to prevent false target detection. As shown in FIGURE 11, the side lobes are attenuated approximately 18db from the main lobe and extend at approximately 225 degree angles. By radiating such known field patterns along each lane of the roadway, the roadway is effectively divided into separate radiation field regions.

It should be apparent to those skilled in the art that in an alternative embodiment of the invention, a back lobe projected from the rear of the antenna, is used to create larger region of known field pattern.

FIGURE 12 illustrates an example of the roadway being divided into known regions by antenna patterns. In FIGURE 12, an antenna element 250 radiates a known field activity pattern along three lanes 252, 254, and 256 of a roadway 258. In the illustrated embodiment, each lane of the roadway is separated by a toll barrier 260. The numerical values in each lane or at each barrier, e.g. (-25) represent the decrease in intensity level of the RF field at each location expressed in db. In the example shown, a signal directed along the center lane 254 establishes an energy gradient that relates to the distance from the antenna element 250. In the illustrated example, the antenna field strength in lane 254 decreases 30db over the forty feet measured from one end of the toll barrier 260 to the far end. As further shown in FIGURE 12, parallel positions within the adjacent lanes 252 and 256 are a minimum of 14db below a parallel point in the center lane 254, (i.e., -65db for the center lane and -79 db for the adjacent lanes). As a mobile transceiver approaches antenna 250, the intensity difference between parallel positions within adjacent lanes increases (i.e. a 45db difference at the point closest to the antenna). In the example shown, the center of each lane is separated from the center of the adjacent lane by a minimum of 14 feet. In this way, the present invention allows transceiver units 218-222 to be spaced apart the typical separation of a conventional toll booth.

As can be seen from the example shown in FIGURE 12, a signal strength measurement of -40db, corresponds to the region of the roadway that is about halfway along defined lane 254. Those skilled in the art will appreciate that the invention can be practiced with other field strength patterns that indicate a position relative to a transmitting unit. Those skilled in the art will further appreciate that the field pattern can be generated by an intermittent or constant transmission or that each field can have independent frequency characteristics.

In one practice of the invention, lane identification information is digitally encoded into the signal broadcast from the transmitting units. For digitally encoded information, data fields are created that establish header information and data information: Field Size

Start File 2 bytes

Lane Identification 4 bits

En JEik bvtes

Those skilled in the art will appreciate that the invention can be practiced in connection with other data field parameters or alternative forms of encoding techniques, such as phase shift keying, manchester encoding or other techniques know in the art.

FIGURE 13A depicts detail of the transponder 228. The transponder includes a data processor 270, a signal receiver 272, connected to an antenna element 273, a decoding means 274, connected to the signal receiver 272, a signal strength detection unit 276, connected between receiver 272 and processor 270, an early warning signal detection unit 278 also connected between receiver 272 and processor 270, a transmitter 280, a memory element 288 is connected to processor 270, and a user interface section 283. A conventional power supply 289 provides the power requirements of the transponder.

The processor 270 can be an 8086 microprocessor or an 8051 microcontroller, or other processor capable of executing the calculations necessary to determine vehicle position. In the embodiment depicted in FIGURE 13 A, decoding means 274, connected to receiver element 272 and processor element 270, decodes the lane identification information encoded in the signal received at receiver 272. In an alternative embodiment, the processor 270 also decodes and inteφrets the encoded signals in a manner described in greater detail hereinafter. The memory element 288, preferably provides sufficient non-volatile memory to store program information including information for processing of signal strength detection information and lane identification information.

The transponder antenna 273, can be incoφorated into the transponder module itself or a receptacle can be provided to attach to a conventional window mounted antenna, similar to those employed in connection with cellular telephone devices.

The user interface section 283 preferably include user operable keys 282, LCD or LED display unit 284, and a audio alarm module 286. The display and audio alarm elements provide visual, audible alarm signals when necessary, while the keys and display elements enable the vehicle operator to obtain information relating to lane position and distance from stationary base units, as well as enter any information that may be required. The display and user interface keys, in combination with conventional stored software routines controlling the processor, enable the user to view information concerning the vehicles position within a lane or along the roadway. In one embodiment, the user interface includes an alpha numeric display having two lines often characters each.

Power supply elements preferably include a compact user replaceable long-life battery 289, such as a lithium power cell. These elements can also include an on/off switch incoφorating a battery check position.

The components depicted in FIGURE 13A are conventional in design and construction, and the transponder can be constructed in accord with known transponder and microprocessor principles. The illustrated transponder can be housed in a compact portable enclosure adapted for removable attachment to a dashboard surface or other convenient location within a vehicle.

The combination of components depicted in the FIGURE 13 A enables the transponder to process signal information and determine its lane position and linear distance from a stationery transmitting unit. Furthermore, the transponder memory 288 can store software and algorithms for determining the position of the moving vehicle relative to the positions of the other lanes on the roadway. As will be described in greater detail hereinafter, the relative position of vehicles traveling along a multi-lane roadway can be transmitted to an automated toll system or other automated traffic management system to determine the sequence of traveling traffic moving along a multi-lane roadway.

In one embodiment of the invention the microprocessor has a low power consumption state, a standby mode, that is used to conserve power. In standby mode the microprocessor halts all activity. The processor is brought out of this mode by activating an input on the microprocessor 270. Conserving power when the transponder is not processing signal position information, reduces average power demands and significantly extends battery life.

FIGURE 13B, depicts the components of an early warning unit as practiced in one embodiment of the invention. The function of the early warning unit is to "wake up" the remainder of the transponder circuit via power switch 294. Filter 290 monitors signals picked up by antenna 273. Filter element 290 is a typical bandpass filter constructed as known in the art and functions to detect specific frequencies within the electromagnetic spectrum. Signals passed from filter 290 are sent to detector element 292 that is constructed from a diode and capacitor array or any other construction known in the art. The detector functions to determine the signal strength of the filtered signal. If the filtered signal has sufficient energy then the detector determines the vehicle to be approaching an antenna field pattern. The detector unit 292 relays a signal to power switch 294. Power switch 294 activates the microprocessor 270.

The signal strength detection unit 276 receives the signal from the receiver unit 272. The signal strength detection unit 276 measures the strength of the received analog signal and performs an analog to digital conversion to generate a digital signal indicative of the signal strength. The digital signal is transferred to the processor 270 for determining the position of the vehicle as will be explained in greater detail hereinafter.

The signal decoding means 274 processes signals sent from receiver unit 272 and decodes the lane identification information transmitted with the signal. The lane identification information is sent to the processor means 270. Processor means 270 tags the measured signal strength with the lane identification signal. The processor then uses the lane identification information and the signal strength information to determine position of the vehicle relative to the transmitting units.

In an alternative embodiment, the carrier is removed from the lane identification information signal and the data is left. The lane identity and error correction information is decoded from a manchester encoded format and checked for errors. Other forms of error correction known in the art can be used to check the integrity of the received signal.

FIGURE 14 illustrates one example of the circuit design for the signal strength detection unit 276. The example depicted in FIGURE 14 is illustrative of one possible construction of a signal strength detection unit that achieves economy, and therefore promotes the use of the present invention.

A signal received by antenna 273 is sent to unit 276. Signal strength detection unit 276 has a storage capacitor 203 of known value so that capacitor 203 charges at a known rate as the signal from receiver 272 is transferred to the capacitor 203. Unit 276 has a omparator element 206 having its inverting input connected to storage capacitor 203. The non-inverting input of comparator element 206 is connected to a bias element 214. The bias element depicted is a simple voltage divider constructed from two resistors 202 and 204. The voltage across resistor element 204 is a constant reference voltage.

The output of the comparator element 206 is connected to a lane detect input pin on the processor element 270. A high state on the lane detect pin indicates that the voltage across capacitor 203 is greater than the reference voltage across resistor 204. The processor element 270 has an output pin connected to the base input of discharge transistor 207. The collector of discharge transistor 207 is connected to the inverting input of the comparator 206 and the signal input of the storage capacitor 203. The processor can reset the storage capacitor 203 by activating the transistor element 207 through its output control pin.

The configuration of elements in FIGURE 14 forms a one bit analog to digital converter that can sample an incoming signal for a specific period of time and compare the collected voltage to a known reference signal. Once the signal is read, the converter is reset, by removing the stored voltage across capacitor 203, and the process runs again. In this way the capacitor 203 and comparator 206 and biasing network 214 form a one bit analog to digital converter that generates a digital signal indicative of the strength of the received signal. The ratio of resistor elements 202 and 204 is chosen to generate a reference voltage on the non-inverting input of the comparator 206 that corresponds to a specific detect signal intensity, for example -40db. Therefore, by checking the voltage across capacitor 203 at specific times, the processor element 270 samples the strength of the antenna field.

Those skilled in the art will appreciate that the invention can be practiced in connection with other field intensity evaluation methods, specifically methods that use discreet analog to digital converters and methods that generate multi-bit representations of the signal strength of the received signal.

In accord with one embodiment of the invention, the transponder is operated in the following manner to determine lane position and linear distance from the stationery transceivers.

Referring again to FIGURE 10, the transponder 228 of vehicle 212 is inactive as it approaches the antenna field 226 of transmitting unit 218. As the vehicle enters field 226, the early warning signal detection unit 278, places the processor 270 in active mode and the transponder begins processing the received signals.

FIGURE 15 is a flow diagram of the processor code for determining the vehicle lane position. As illustrated in FIGURE 15, once the processor 270 is in active mode, the processor waits for the receiver unit 272 to send it the demodulated signal information. The processor 270 decodes the signal identification information and determines the identity of the lane that transmitted the received signal. The processor then resets the signal strength evaluation unit 276, so that this circuit is initialized to zero. The processor then waits a period of time for the signal strength evaluation unit to determine the strength of the signal. In the example given the processor element 270 waits 50 milliseconds, allowing the capacitor 203 to charge. At the end of 50 milliseconds the processor reads and stores the signal strength from this circuit. Processor 270 then compares the measured signal strength to the known field pattern of the transmitting unit. If the signal strength indicates the vehicle is within the identified lane then the lane position counter associated with that lane identity is incremented. The processor then determines from a preset counter whether enough lane detections have been recorded to indicate a probability of the lane identification. In one example, five consecutive detections of a signal transmitted from the same lane, with a signal strength indicating the vehicle is in that lane, is sufficient to identify the lane position of the vehicle. Once the lane identity has been checked the signal strength, the processor returns to a wait condition.

In a further embodiment of the invention, the determined lane identification information is stored by the processor 270 in a register of memory 288. The lane identification information along with preassigned vehicle identity information, is then encoded into all signals transmitted from transponder 228 to the stationary transceiver units 218-222. In one example, transmitting units 218-222 are positioned above the lanes of an automated toll collection plaza or gentry. Transceiver units 218-222 control signals to vehicles approaching the tolls that require the vehicles to transmit information signals back to the transceiver unit above that vehicle's lane. In an apparatus constructed in accordance with the present invention, processor 270 retrieves the lane identity from the memory 288 and transmits the lane identity, along with other information, to the transceiver units 218-222. In this way, transceiver units 218-222 overcome the problem of multi-pathing by correlating each received signal to the correct vehicle.

In another aspect of the invention, a method for determining the position of a vehicle traveling on a multi-lane roadway is determined by the following steps. In the first step a transceiver unit is positioned above one lane of a multi-lane roadway and transmits through a highly directional antenna a signal encoded with lane identification information.

In a second step, a mobile transponder unit receives transmitted signals and processes these signals to determine lane information identification and the strength of the signal information. In a third step the lane identification information and signal strength information is processed to determine the vehicle lane position and distance from the stationary transceiver unit.

A further method comprises storing the lane identification information, so that it can be encoded in al transmissions from the mobile transponder to the transceiver units, in this way allowing the transceiver units to establish the lane position of the transmitting vehicle. Toll Enforcement System

Figure 16 depicts schematically the general features of a toll enforcement system 300 that can, in one practice, be employed with the above described automated toll collection system. The illustrated toll enforcement system 300 includes a toll plaza 302 extending over the roadway 304, on which the vehicles 306, 308, and 310 travel. The system 300 further includes a vehicle detector 318, a beacon detector 320 and a recording unit 312 that has image collection elements 322A-322C. An optional transmitter 324 can be positioned adjacent the roadway 304 at a position on the roadway downstream from the toll plaza 302. As illustrated, the vehicles 306 and 310 carry IVC units 306' and 310' and the vehicle 308 is traveling along the roadway 304 without an IVC unit. The enforcement system 300 can detect among the vehicles approaching the toll plaza 302, those vehicles that fail to pay the required toll assessed by the collection system.

In the illustrated embodiment of the toll enforcement system 300, each vehicle traveling along the roadway 304 is capable of changing between the lanes on the roadway 304 and can pass through the toll plaza 302 without interruption. Consequently, the illustrated embodiment enables automatic collection of toll charges from vehicles moving through the toll plaza 302 at speeds between zero and approximately one hundred m.p.h. Vehicles need not halt or slow down significantly for toll collection.

The enforcement system 300 includes IVC units that have a beacon signal generator 490 that can generate a beacon signal which indicates whether or not the vehicle traveling on the roadway 304 is authorized to pass the toll plaza 302. In one aspect of the invention, the beacon signal is an optically detectable signal that can be identified within an image of the vehicles moving along the roadway 304. In this aspect of the invention, the optically detectable beacon signal can act as a marker that can be detected by an imaging system that acquires images of the vehicles on the roadway 304, and can be employed by the imaging system as a marker that distinguishes between authorized and unauthorized vehicles.

The vehicle detector 318 can detect each vehicle 306, 308, and 310 traveling on the roadway 304 and can track the position of each vehicle as it moves toward the toll plaza 302. The beacon detector 320 can examine each vehicle detected by the vehicle detector 318 to determine if the vehicle is generating a beacon signal. Any vehicle traveling on the roadway 304 that is detected by the vehicle detector 318 and that fails to generate a beacon signal can represent an unauthorized vehicle traveling along a toll roadway, such as the roadway 304.

The system 300 can track any unauthorized vehicle as it passes through the toll plaza 302 and can record select characteristics of the unauthorized vehicle as it passes the collection element 322A-322C. The recording unit 312 connects to the collection elements 322A-322C, and can generate from the collected data, vehicle record signals that represent characteristics of the unauthorized vehicle traveling on the roadway 304. The collection elements can be sensor elements, such as cameras, treadles, scales or other sensing devices that can generate a signal representative of one or more distinguishing characteristics of the unauthorized vehicle, such as the its license plate number, the number of axles, the vehicle weight, color or other characteristic.

In certain embodiments of the invention, as will be explained in greater detail hereinafter, the vehicle detector 318 includes a camera element 314 for generating images of the vehicles approaching the toll plaza 302. The vehicle detector camera element 314 can optionally connect to the recording unit 312 to store the images of the approaching vehicles. The recording unit 312 can store the vehicle images in a computer memory. In this way, the recording unit 312 builds a database memory of the unauthorized vehicles that have been detected by the system 300. In one practice of the invention, a law enforcement officer reviews the images in the database and identifies the offending vehicles.

The illustrated toll enforcement system 300 includes two primary active components. The first component is a beacon signal generator 490 located in each of the vehicles traveling along the roadway 304. In a preferred embodiment of the invention, the beacon signal generator 490 is incoφorated into the IVC purchased or leased by the vehicle operator. As previously described, the IVC contains a transponder, a microprocessor, a memory for storing, manipulating, and reporting on a qw-αtity representative of money available to the vehicle for debiting toll transactions, and includes, in this embodiment, a beacon signal generator 490 for generating a beacon signal that represents the authority of the vehicle to travel through the toll plaza 302. Therefore, in one embodiment of the invention, an IVC controls and processes toll related debit/credit transactions and generates a beacon signal to the beacon detector 320 at toll plaza 302 to inform the toll plaza 302 that the vehicle is authorized to pass through the toll plaza 302.

The second primary active component is an authorization detection and enforcement system that detects the authorization for each vehicle to pass through the toll plaza 302. The authorization detection and enforcement system includes the vehicle detector 318, the beacon detector 320 and recording unit 312. The vehicle detector 318 detects each vehicle moving along the roadway 304. The beacon detector 320 examines each detected vehicle to determine if the detected vehicle is transmitting a beacon signal. Each detected vehicle that fails to transmit a beacon signal is tracked by the vehicle detector 318 as it moves through the toll plaza 302. The recording unit 312 is activated as the offending vehicle passes through the toll plaza 302. The collection elements 322A-322C and the camera element 314 can record select characteristics of the offending vehicle. The illustrated collection elements include three camera elements 322A-322C. The first camera element 322A is connected to the gantry 302 that extends over the roadway 304. The camera element 322A records an overhead perspective of the roadway 304 as an unauthorized vehicle passes out of the toll plaza 302. Similarly, the recording unit 312 can include camera elements 322B and 322C positioned on the sides of the roadway 304 for generating image signals having a side perspective of an unauthorized vehicle passing out of the toll plaza 302.

As stated above, the vehicle detector 318 can include a processing unit 316, such as a conventional unix based computer system with a video acquisition circuit assembly that connects via a transmission path, such as a coaxial cable, to the camera element 314. The camera element 314 can transmit the acquired images to the processing unit 316. In one preferred embodiment of the invention, the camera element 314 transmits the acquired images as video images, and employs a standard video signal protocol, such as the RS-170 video signal standard that defines a composite video and synchronizing signal, having a frame size and frame rate for images transferred with two interleaved fields, and a 4:3 horizontal to vertical aspect ratio. It should be apparent to one of ordinary skill in the art of video systems, that other cameras, and standards, or proprietary systems, can be practiced with the present invention without departing from the scope thereof.

In a preferred embodiment of the invention, the camera element 314 includes a solid- state camera incoφorating a charge coupled device (CCD). The camera element 314 can include an infra-red filter 326 to reduce broad-band sensitivity to infra-red and near-infra-red radiation between 800 and 1 100 nm. This filter 326 reduces the interference caused by ambient infra-red light. In one embodiment, the filter 326 can be a thin-film filter that selectively passes infra-red light at the frequency of an infra-red beacon signal and the selected frequency can be in the range of 1100 - 1500 nm. Alternative structures for an infra¬ red filter including dichroic filters, holographic filters and other filter constructions can be practiced with the present invention without departing from the scope thereof. Furthermore, modifications to the filter 326 can be made, including adding polarizing filters, and other optical elements, to enhance the signal-to-noise ratio for information signals in the select band broadcast by an optically detectable beacon, without departing from the scope of the invention.

As stated above, the vehicle detector 318 can include an image processing unit 316 having an object recognition system that can identify vehicles approaching the toll plaza 302. The vehicle detector 318 can detect, identify and track vehicles moving in the field of view 328. In the preferred embodiment, the field of view 328 is selected to include the portion of the roadway 304 that extends between 4 to 300 meters from the toll plaza 302 toward the transmitter 324, and preferably extends across each lane of the roadway 304. In the illustrated embodiment the field-of-view 328 begins at the camera element 314 and extends for approximately 300 meters. At 20 meters from the camera element 314, the field of view 328 has a payment violation point 330. The illustrated payment violation point 330 indicates the point in the field of view 328, and therefore on the roadway 304, where the beacon detector 320 can activate the enforcement signal to record an unauthorized vehicle approaching the toll plaza 302.

It should be apparent to one of ordinary skill in the art of image processing that the camera element CCD is composed of an array of light sensitive devices that can correspond to pixels in an image. The pixel data can correspond to a region of the acquired image and therefore, can correspond to a physical portion of the roadway 304 in the field of view 328. As each point in the field of view 328 can map to a physical point on the roadway 304, the vehicle detector 318 can track the position of each vehicle approaching the toll plaza 302.

The vehicle detector 318 can include an object recognition system that identifies a vehicle signature for each object moving in the field of view 328. The vehicle signature signal generated by the illustrated vehicle detector 318 can be an image signature that uniquely identifies each object detected in the field of view 328. Alternative systems for object detection can generate other vehicle signatures that uniquely identify each vehicle approaching the toll plaza 304. The vehicle detector 318 can employ an object recognition system to generate the image signature signals from the image acquired by the camera element 314. The object recognition system can include a video image processing system for performing image analysis of the acquired image signals. The image processing system can be a conventional computer processing system, and preferably is a unix based computer system connected to a local area network.

The object recognition system can implement an image analysis software program that extracts information from the acquired images for high level scene analysis and for classification of image segments to detect vehicles moving in the field of view 328. The image analysis software can generate a list of detected vehicles, each identified by an image signature and a position signal that represents the position of the associated vehicle relative to the camera element 314. The image analysis software can include spatial filters for increasing the signal to noise ratio of image features and can include feature extraction for converting the acquired, filtered images into primitive features such as edges, colors, textures and other features that are definitive of an object moving along a known background, such as an asphalt roadway. Any of the common edge detection techniques can be employed by the present invention, including color transition detection that determines the magnitude and the direction of the changes in pixel intensity within the acquired image. The magnitude and direction can be computed from the partial derivatives of the image as a function of the horizontal and vertical axes of the image, g (x, y), where g represents pixel intensity or color, and x and y represent, respectively, the row and column of the associated pixel. The information obtained from applying the derivative operators allows segmentation of the image which can be a first step toward object identification. The image processor can include a time stamp generator that allows the images to be analyzed one frame at a time and give a time stamp reference for determining how quickly the vehicle is moving on the roadway.

The image edge detection can be performed by 2-D convolution of the image or any other edge detection scheme suitable for detecting images in real time. The image analysis system can employ shape analysis for inteφreting the extracted features into a shape.

Techniques, such as the Hough Transform for line detection, are well known in the art of image analysis for determining straight lines or curves. Higher level features, such as object outlines, can be generated from the identified shapes and lines. Objects can be distinguished and uniquely identified by any of the common techniques, including relative location of the object, characteristic pattern features of the object, such as the surface area of identified object, or the composite features such as the surface area of the object relative to the perimeter size of the object.

The object recognition system can generate a list of the identified vehicles in the field of view 328, and can track the position of each vehicle relative to the camera element 314. It should be apparent to one of ordinary skill in the art of image processing, that other object detection systems that can detect in real time objects moving against a known background image can be practiced with the present invention, without departing from the scope thereof. Furthermore, the illustrated embodiment depicts one preferred system for detecting vehicles moving along a roadway 304. Alternative object detection techniques and systems, can be practiced with the present invention including a separate camera element for imaging vehicles in each lane of the roadway 304, treadles extending across the lanes, or a system that employs the radio frequency positioning system illustrated in FIGURE 10 that includes the lane transmitting units 218-222, that have phased array antennas that radiate energy along a main lobe extending down a known lane of the roadway 258. The antennas can include a beamforming receiver that detects the presence and position of vehicles on the roadway 304. Other object detection techniques can be practiced with the present invention without departing from the scope thereof.

The beacon detector 320 detects beacon signals generated by the beacon generator

490 in the IVCs carried in the vehicles moving along the roadway 304. In the system 300 illustrated in Figure 16, the beacon detector 320 connects to the camera element 314 via a transmission path such as a coaxial cable, and also connects to the vehicle detector 318. The illustrated beacon detector 320 optically detects beacons generated by the IVC units in the vehicles traveling along roadway 304 and within the field of view 328. The beacon detector 320 can receive the list of detected vehicles generated by vehicle detector 318 that identifies each vehicle within the field of view 328 and the position of that vehicle relative to the camera element 314. The optical beacon detector 320 can analyze, for each detected vehicle, the image of that vehicle captured by the camera element 314. The illustrated optical beacon detector 320 can inspect the captured image to identify the presence of a beacon signal, such as an infra-red burst of energy, that is being generated by an optically detectable beacon source at the position of the detected vehicle. If the beacon detector 320 determines that there is a beacon signal at a position that is coincident with one of the identified vehicles, that beacon detector 320 can identify the vehicle as an authorized vehicle that includes a beacon generator that is actively generating a beacon signal as it approaches the toll plaza 302. Alternatively, if the beacon detector 320 analyzes the image of a vehicle approaching the toll plaza 302 and determines that the image of the approaching vehicle fails to indicate the presence of a beacon signal, the beacon detector 320 can determine that this vehicle is an unauthorized vehicle, failing to generate a beacon signal and approaching the toll plaza 302. Each time the beacon detector 320 determines an unauthorized vehicle is traveling toward the toll plaza 302, the beacon detector 320 can generate an enforcement signal 332 that can activate an enforcement mechanism for enforcing the toll payments at the toll plaza 302.

In one embodiment of the invention, the beacon detector 320 can detect beacon signals that toggle while passing through the field of view 328. In this embodiment, the beacon generator 490 can generate a beacon signal at a certain point in the field of view and can deactivate the beacon signal at a second point. The beacon detector 320 can have a pulse detection system that detects the toggled beacon signal by comparing successive image frames. The toggled beacon signal increases the resistance to imposters traveling on the roadway 304. Other systems and techniques can be practiced with the present invention, including a detector that detects the rate at which the beacon signal toggles, and beacon generators 490 that toggle at a rate selected by the system 300 and transmitted to the IVC via the transmitter 324.

As previously described, the camera element 314 can include an infra-red filter element 326 that allows a select band of energy to pass onto a CCD element in the camera element 314. A video signal generated by the car-^ra element 314 transmits to the beacon detector 320 that includes a video acquisition int iace for receiving the video signal generated by the camera element 314. The illustrated beacon detector 320 can include an image analysis system that has filters for filtering the images acquired by the camera element 314 to identify those regions of the acquired image that include data representative of an energy source that radiates energy in the select frequency range. The detected regions of the image correspond to certain pixel locations within the CCD element, that correspond to certain positions on the roadway 304. The beacon detector 320 can generate a list of beacon positions for each image frame in the video signals acquired by the camera element 314.

The vehicle detector 318 can transmit to the beacon detector 320 the list of detected vehicles and the position of the detected vehicles. The beacon detector 320 can coordinate the relative positions of the detected beacon signal sources with the relative positions of the detected vehicles, and with desired units information transmitted from IVCs in that vehicle, and generate a list of authorized vehicles traveling on roadway 304 and approaching the toll plaza 302 and a list of unauthorized vehicles traveling along the roadway 304. The beacon detector 320 can generate the lists of authorized and unauthorized vehicles, in real time, or in near to real time, to correspond to the vehicles presently traveling on the road 304 and approaching the toll plaza 302. In this way, the beacon detector 320 generates a computer processable profile of the vehicles that are traveling along the roadway 304 at any given time.

The beacon detector 320 can generate an enforcement signal 332 any time one or more unauthorized vehicles are detected on the roadway 304. The enforcement signal 332 can be transmitted to an enforcement mechanism that requires an unauthorized vehicle to comply with the toll collection requests generated by the toll plaza 302. In one embodiment of the invention the enforcement signal 332 generated by the beacon detector 320 can activate an enforcement mechanism that visibly displays, on a sign positioned at the forward portion of the toll plaza 302, an order to the unauthorized vehicle to move to a manual toll collection booth within the toll plaza 302 for manually paying the requisite toll fee. Alternatively, the enforcement system can include a visual display located at a portion of the roadway traversed by the vehicles after passing through the toll plaza 302. The visual display can generate a visual signal to a law enforcement official positioned along the side of the roadway to inform the law enforcement official that a vehicle passing through the toll plaza 302 has failed to comply with a toll request. Alternative techniques and systems for enforcing payment of the assessed toll, some of which will be explained in greater detail herein after, can be practiced with the present invention without departing from the scope thereof.

In a preferred embodiment of the invention, the enforcement signal 332 is transmitted via a transmission path to the recording unit 312. The recording unit 312 can include sensor elements for recording certain characteristics of the vehicles traveling through the toll plaza 302. In the illustrated embodiment the recording unit 312 couples via video transmission cables to the camera element 314 and the collection units 322A-322C. The illustrated recording unit 312 can record and store image signals of the vehicles and passing the toll station 302. In the depicted embodiment, the collection units 322A-322C are video camera elements positioned proximate to the roadway 304 for collecting visual images of any vehicle passing through the toll station 302. Figure 17 illustrates from a side perspective, one embodiment of the toll enforcement system 300 previously described. The camera element 314 generates video images of the vehicles approaching the system 300. The image analysis system of the beacon detector 320 can detect a beacon signal, such as infra-red lights, generated by the IVC units carried in the approaching vehicles. In one embodiment of the invention, the beacon detector 320 includes a video mixer unit that generates a composite video signal that includes the images of the approaching vehicles and the images that represent the detected beacon signal. In one embodiment, the beacon signal is represented in the composite video signal as a visible light source positioned behind the windshield of the approaching vehicles. The composite video signal is transmitted to the recording unit 312 where it can be stored for later analysis. It should be apparent to one of ordinary skill in the art of image acquisition and processing that alternative techniques for generating video images of the approaching vehicles that distinguished between vehicles having activate beacon generators and vehicles without active beacon generators can be practiced with the present invention. These techniques and systems can include beacon generators that generate an optically detectable beacon signal at a frequency that causes the image of an approaching vehicle captured by the camera element 314 to have a washed out characteristic that indicates the presence of an active beacon generator. The signal processing systems that can employ spatial filters that detect the washed out characteristic and that can process the generated image signals. These image processing systems can be constructed in accord with signal processing and microprocessor principles which are well known in the art of electrical engineering.

The camera element 322A depicted in Figure 17 generates video signals representative of a rear overhead perspective of any vehicle traveling past the toll plaza 302. Similarly the camera elements 322B and 322C are positioned adjacent to the road 304 for collecting side and rear perspectives of any vehicle traveling through the toll station 302. Preferably the camera elements 322B and 322C are positioned and angled for acquiring images of a vehicle's license plate as the vehicle travels past the camera elements 322B and 322C. The enforcement signal 332 can activate the recording unit 312 to store the acquired video images from the camera elements 314 and 322A-322C that record an unauthorized vehicle passing through the system 300. Typically, the video images from the different camera elements are formatted into vehicle records that include images and other information collected by the system 300 over a period of time, such as three seconds, that approximately corresponds to the time period when the unauthorized vehicle is passing through the system 300. The stored vehicle records can be maintained in a memory element that includes a video buffer memory 340, a memory control circuit 342 and a console memory 344. - 50 -

The video buffer memory 340 connects to the interface of recording unit 312 to receive the enforcement signal 332 generated by the beacon detector 320. The video buffer memory 340 can connect to each of the camera elements 314, 322A-322C to receive the video image signals acquired by these camera images and to temporarily store these elements in a buffer memory. The memory control circuit, upon detecting the enforcement signal 332 going active, can store a select portion of the video signals in the video buffer memory 340 into the console memory 344. The video console memory 344 can store these select signals for later review by a law enforcement official who can examine these signals and identify the offending vehicle.

The video buffer memory 340 can be an electrical circuit card assembly of the type commonly used for storing electrical digital data signals representative of information. In a preferred embodiment, the video buffer memory 340 is a random access memory that can receive and transmit data. Data can be received from the camera elements 314 and 322A - 322B and can be transmitted to the console memory 344. The memory control circuit 342 can control the transfer of data from the video buffer memory 340 to the console memory 344. The video buffer memory can be arranged for storing video image signals captured by the camera elements 314, 322A through 322C. In one embodiment, the video buffer memory 340 continuously stores the image information to maintain a real time data base of the images captured by the camera elements 314 and 322 A- 322C over the preceding time period. This continuous buffer memory 340 can be constructed as a FIFO memory that writes over the stored data each time the memory fills.

Memory control circuit 342, in response to the enforcement signal, can activate the video buffer memory 340 to store the contents of the video buffer memory into the console memory 344. The console memory 344 can be a electrical circuit card assembly of the type commonly used for storing electrical digital data signals. The console memory can be a random access memory that stores the signals from the video buffer memory 340 as vehicle record signals. Alternatively, the console memory 344 can be a hard disk drive connected to a workstation having a monitor. The video record signals stored on the hard disk drive console memory 344 can be reviewed by a law enforcement official operating the workstation and viewing the stored video images to identify the unauthorized vehicle passing through the toll plaza 302. The workstation (not shown) can be a unix based data processing system that allows the video record signals to be viewed on a monitor. The video record signals can represent image signals captured by each of the camera elements. The workstation can display the images captured by each camera element, separately in a distinct window of the monitor. In this way the law enforcement official can simultaneously view all the images captured by the distinct camera elements. Figure 17 illustrates a preferred embodiment of the invention that includes sensor elements 350 for collecting characteristic information of the vehicles traveling on the roadway 304 and for generating a class signal that can be visually displayed by the light bar 352, described with reference to Figure 6 and that includes the vertical array of indicator lights 1 12 housed within a weatheφroof, substantially cylindrical enclosure. Each indicator light in the light array represents a different class of vehicle — bus, car, truck, or other. Separate indicator lights can be provided for each lane on the roadway 304. As previously described, the microprocessor 1 16 controls the switch 114 to energize a selected indicator light, in response to signals from the sensor elements 350. The sensor elements 350 illustrated in Figure 17 can include treadle sensors that can detect the number of axles on the vehicle traveling in the respective lane. In one embodiment, the number of axles can indicate the class of vehicle passing through the toll plaza 302 and can generate a class signal transmitted via a transmission path to the light bar 352.

As illustrated, the light bar 352 can be positioned adjacent the roadway 304 to be optically coupled with the camera collection element 322B so that the image of the light bar 352 is acquired along with images of the vehicles. If the sensors 350 indicate a class of vehicle that does not correspond to the vehicle class indicated by the IVC, the processor 116 can generate a signal to the recording unit 312 that activates the memory control circuit 342 to store the recorded images. Enforcement personnel can then monitor the recorded image of the light column for each automated lane to confirm proper correspondence between visually observed vehicle class and vehicle class indicated by light bar 352. Lack of proper correspondence indicates that the IVC in the vehicle is incorrectly initialized for the class of vehicle in which the IVC is installed.

Figure 18 depicts in detail one IVC transponder 428. The IVC transponder 428 includes a data processor 470, a signal receiver 472, connected to an antenna element 473, a decoding means 474 connected to the signal receiver 472, a signal strength detection unit 476 connected between the receiver 472 and the processor 470, an early warning signal detection unit 478 also connected between the receiver 472 and the processor 470. Through transmitter 480, a memory element 488 is connected to processor 470 and a user interface 483. The conventional power supply 489 provides the power requirements of the IVC transponder 428.

The IVC transponder depicted in Figure 18 includes a beacon generator 490 that generates the beacon signal that can be detected by the beacon detector unit 320. The IVC transponder 490 connects to the processor 470 by a transmission path that can act as a control line for activating the beacon generator 490. The illustrated beacon generator 490 includes a light emitting diode 492 that can be positioned externally to the casing that encloses the IVC transponder 428. Preferably the light emitting diode 492 is positioned on the housing of the IVC transponder 428 so that the light emitting diode 492 is directed at the windshield of the vehicle. In this way the radiation produced by the light emitting diode 492 is directed at the windshield of the vehicle, and is readily detectable by the camera element 314.

In one embodiment of the invention, the IVC unit 428 includes a processor element 470 that has an operation program that generates an activation signal to the beacon generator 490 in response to a signal transmitted from the transmitter 324.

In a preferred embodiment of the invention, the diode 492 is an infra-red light emitting diode that emits light of sufficient intensity to be detected by the camera element 314 at a distance of up to 200 meters. However, it should be apparent to one of ordinary skil in the art of image processing that other beacon generators can be employed by the present invention to generate a beacon signal detectable by a sensor element. In one aspect, other optically detectable beacon generators can be employed, including near-infra-red light emitting diodes, ultra-violet light sources, tunable laser diodes, and visible light sources. Moreover, combinations of optically detectable beacon generators can be employed to generate more easily detectable beacon sources, and beacon signals more easily detected under harsh environmental conditions, including rain and fog.

As previously described, the processor 470 calculates the requisite toll for proceedin through toll plaza 302. The processor 470 can debit a cache responsive to the required toll and generate an acknowledge signal that can be transmitted to the toll plaza 302. The illustrated embodiment the IVC transponder 428 can transmit the acknowledge signal via the transmission path that connects the processor 470 to the beacon generator 490. Responsive t the detection of an active acknowledge signal, the beacon generator 490 can activate the diode 492. Preferably the LED 492 is a light emitting diode that has a maximum continuous output of approximately 500 milliwatts at a wavelength of 1,300 nanometers. The beacon generator 490 can continuously activate the light emitting diode 492 responsive to the acknowledge signal generated by the processor 470. In a preferred embodiment of the beacon generator 490, the generator deactivates the diode 492 responsive to a signal from th processor 470 generated after the IVC unit generates an acknowledge signal to the toll plaza 302. Alternatively, the beacon generator 490 can include a timing circuit that counts down a selected time period during which the diode 492 is continuously operated. When the timing circuits indicates that the diode 492 has been active for the selected period of time, the beaco generator 490 can deactivate the diode 492. Alternatively, the beacon generator 490 can operate the diode 492 in a burst mode, to generate a pulse train of infrared signals that can b detected by the beacon detector 320. In an alternative embodiment of the present invention, the IVC transponder 428 includes a processor 470 that can detect a deactivation signal received by the receiver unit 472 through the antenna 473. In this practice of the invention a deactivation transmitter is positioned adjacent to the roadway 304 at a location that is traversed by the vehicles after having passed the toll plaza 302. Deactivation transmitter can transmit a deactivation signal that is received by the receiver 473, decoded by the decoding unit 474 and operated on by the processor 470, to generate a deactivation signal that causes the beacon generator 490 to deactivate the LED 492.

With reference again to Figure 16, a further aspect of the present invention can be described. As illustrated in Figure 16, the transmitter 324 is located adjacent to the roadway 304 in a position upstream from the toll plaza 302, and in the illustrated embodiment, upstream from the field of view 328. The transmitter 324 can broadcast a message to all vehicles traveling along the roadway 304 and approaching the toll plaza 302. The transmitter 324 can include a broadcast antenna and a control unit which houses a radio transmitter and a digital interface board. The digital interface board can connect back to the system 300 via a transmission path, such as a local area network connection, to operate in response to control signals generated by the vehicle detector 318. The vehicle detector 318 can generate control signals that activate the transmitter 324 to broadcast a black list signal to each vehicle approaching the toll plaza 302. The transmitter 324 can continuously broadcast the black list signal so that each IVC unit 428 carried in the vehicle receive the broadcast black list signal. The black list signal can represent a list of vehicle identification numbers that represent vehicles which are not authorized to travel through the toll plaza 302. The black list signal can include vehicle identification numbers of past toll offenders or other vehicles that are not authorized to pass through the toll plaza 302, or are not authorized to drive on the roadway 304.

The IVC transponder units 428 carried in the vehicles receive the black list signal and operates according to a software program to compare the vehicle identification numbers contained in the black list to the vehicle identification number stored in the memory element within the IVC. If the processor 470 determiner that the vehicle identification number stored in the memory elements 488 corresponds to a vcnicle identification number broadcast from the transmitter 324 the processor 470 can disable the beacon generator 490, so that the beacon generator 490 cannot activate the beacon signal. In this way, the black list signal acts as an override that can deny a vehicle the authority to pass through a toll plaza, despite the vehicle's ability to pay the requisite toll.

It will thus be seen that the invention efficiently attains the object set forth above, among those made apparent from the preceding description. In particular, the invention provides systems and methods for detecting toll violators proceeding through an automated toll collection system. The invention thereby enables high levels throughput through toll collection stations that are unattainable but conventional toll collection systems.

It is accordingly intended that all matter contained in the above description or shown in the accompanying drawings be inteφreted as illustrative rather than in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention as described herein, and all statements of the scope of the invention which, as a matter of language, might be said to fall there between.

Having described the invention, what is claimed as new and secured by Letters Patent is:

Claims

Claim≥:

1. Apparatus for detecting and recording select characteristics of a vehicle traveling on a roadway, comprising vehicle detector means, positioned adjacent to a portion of the roadway, for detecting vehicles traveling on the roadway portion, said vehicle detector means including an image acquisition element for acquiring images of the vehicles traveling on the roadway, and for generating image signals representative of said acquired images, and processing means for generating, from said image signals, image signatures representative of each vehicle detected on the roadway and for generating a tracking signal for each detected vehicle, representative of the position of the vehicle relative to said vehicle detector means, beacon detector means for detecting beacon signals generated by select ones of said detected vehicles and for generating an enforcement signal representative of a vehicle failing to generate a beacon signal, and a recorder unit, in communication with said beacon detector means and said vehicle detector means and positioned adjacent to the roadway, for generating vehicle record signals representative of select characteristics of each said vehicle traveling on the roadway portion and having memory means for storing said vehicle record signals of said vehicles failing to generate a beacon signal.

2. Apparatus according to claim 1 wherein said beacon detector means includes means for detecting an infra-red beacon signal.

3. Apparatus according to claim 2 wherein said infra-red beacon signal detector includes means for detecting infra-red image data collected by said camera element.

4. Apparatus according to claim 1 wherein said beacon detector means includes a filter element in communication with said camera element for filtering said image signals to detect image signals of specific wavelengths.

5. Apparatus in accordance with claim 4 wherein said filter element filters image signals of infra-red wavelengths.

6. Apparatus according to claim 1 wherein said image acquisition element includes a CCD element.

7. Apparatus according to claim 1 wherein said image acquisition element is a camera.

8. Apparatus according to claim 1 wherein said image acquisition element is a video camera.

9. Apparatus according to claim 1 wherein said image acquisition element includes a wide angle lens element optically coupled to the portion of the roadway.

10. Apparatus according to claim 7 wherein said camera element includes a plurality of camera units each optically coupled to select areas of the roadway portion.

11. Apparatus according to claim 1 wherein said recorder unit includes a camera element optically coupled to a select area of the roadway portion.

12. Apparatus according to claim 1 wherein said recorder unit includes a camera element mounted to a gantry extending over the portion of the roadway and being optically coupled to the roadway to generate vehicle record signals having an overhead perspective of vehicles traveling on the roadway.

13. Apparatus according to claim 1 wherein said recorder unit includes a camera element mounted at the side of the roadway portion and having an optical path extending transverse to the roadway to generate vehicle record signals having a side perspective of the vehicles traveling on the roadway.

14. Apparatus according to claim 1 wherein said recorder unit memory means includes a buffer memory circuit for temporarily storing said generated vehicle record signals and a console memory for storing select vehicle record signals, and a memory control circuit for storing said select vehicle record signals in said console memory in response to said enforcement signal.

15. Apparatus according to claim 14 wherein said vehicle record signals include images of a license plate of each vehicle traveling on the roadway.

16. Apparatus according to claim 1 for use with vehicles that generate a beacon signal in response to an activation signal, and further comprising transmitter means positioned at a select position adjacent to said portion of the roadway for transmitting said activation signal to said vehicles.

17. Apparatus for automatically collecting a toll or detecting a toll violation, comprising in vehicle processors carried in select vehicle moving along a roadway and having a processor element arranged to calculate a toll amount to be paid at a toll facility positioned along the roadway and for generating a fee paid signal representative of payment of the toll, a transmitter for transmitting, in response to the fee paid signal, an acknowledgment signal to the toll facility to indicate that the calculated toll amount has been paid, and a beacon generator for radiating, in response to the fee paid signal, a beacon signal to indicate that the vehicle is authorized to travel through the toll facility, vehicle detector means, positioned adjacent to a portion of the roadway, for detecting the vehicles approaching the toll facility, said vehicle detector means including an image acquisition element for generating image signals representative of images of the vehicles traveling on the roadway portion, and processing means for generating from said image signals, a vehicle detection signal representative of each detected vehicle approaching the toll facility, and beacon detector means for detecting beacon signals and for generating an enforcement signal representative of a vehicle approaching the toll facility and failing to generate a beacon signal.

18. Apparatus according to claim 17 further comprising a data transmitter positioned along the roadway for broadcasting information signals to vehicles approaching the toll facility, said information signals including a blacklist signal that represents a list of vehicle identifications of respective vehicles that are not authorized to travel through the toll facility, and said in vehicle processor includes a memory element for storing a vehicle identification signal representative of the vehicle carrying said in vehicle processor, and disable means for comparing said blacklist signal with said stored vehicle identification signal to generate a disable signal that prevents the beacon generator from radiating said beacon signal, when said vehicle identification is on said blacklist.

19. Apparatus according to claim 18 wherein said disable means couples to said beacon generator to deactivate said beacon generator.

20. Apparatus according to claim 17 wherein said disable means couples to said processor element to disable the processor from generating the fee paid signal.

21. Apparatus according to claim 20 wherein said data transmitter is positioned adjacent to a portion of the roadway traversed by the vehicles approaching the toll facility.

22. Apparatus according to claim 20 wherein said data transmitter is positioned at the toll facility.

23. Apparatus according to claim 20 wherein said data transmitter includes a radio-frequency transmitter for broadcasting said information signals.

24. Apparatus according to claim 20 further comprising a deactivation transmitter positioned adjacent a portion of the roadway traversed by the vehicles after they pass through the toll facility, for transmitting a deactivation signal that indicates that the vehicle has passed the toll facility ands can deactivate the beacon generator.

25. Apparatus according to claim 20 further including a recorder unit, in communication with said beacon detector means and said vehicle detector means and positioned adjacent to the portion of the roadway, for generating vehicle record signals, as a function of said enforcement signal, and representative of select characteristics of each of said vehicles traveling on the roadway portion and having memory means for storing said vehicle record signals of said vehicles failing to generate a beacon signal.

26. Apparatus according to claim 25 wherein said recorder unit includes a camera element optically coupled to a select portion of the roadway.

27. Apparatus according to claim 25 wherein said recorder unit includes a camera element mounted to a gantry extending over the roadway and optically coupled to the roadway to generate image signals having an overhead perspective of vehicles traveling on the roadway.

28. Apparatus according to claim 25 wherein said recorder unit includes a camera element mounted at the side of the roadway and having an optical path extending transverse to the roadway to generate image signals having a side perspective of the vehicles traveling on the roadway.

29. Apparatus according to claim 25 wherein said recorder unit memory means includes a buffer memory circuit for storing said vehicle record signals for each detected vehicle traveling on the roadway portion, and a memory control circuit for deleting said vehicle record signals for said vehicles which generates a beacon signal.

30. Apparatus according to claim 25 further comprising sensor elements disposed at said toll facility for detecting select characteristics of said vehicles passing through said toll facility, class signal generator for generating a class signal representative of the class of the associated vehicle, anomaly generator for comparing toll data with select characteristics and for detecting a toll violation

31. Apparatus according to claim 25 wherein said class signal generator includes a light bar for generating a visually detectable class signal.

32. Apparatus according to claim 25 wherein said sensor elements include treadles.

33. Apparatus according to claim 25 wherein said sensor elements include a scale.

34. An enforcement system for a toll roadway, such system comprising image acquisition means for making camera images of approaching traffic including vehicles which are to pay tolls, storage means, including a buffer storage, for temporarily storing images from said image acquisition and enforcement storage for permanently storing images, and discrimination means operative on the images produced by said image acquisition means for visually detecting toli offenders in said approaching traffic, wherein the system responds to detection of a toll offender by storing images of the offender from the buffer storage in the enforcement storage.

35. An enforcement system according to claim 34, further comprising tracking means for signaling in which traffic lane a detected offender is traveling.

36. An enforcement system according to claim 34, wherein the discrimination means detects presence or absence of a light emitting beacon on an imaged vehicle to determine if the imaged vehicle carries a toll authorizing device.

37. An enforcement system according to claim 34, wherein the image acquisition means includes a first video camera aimed ahead of a toll station to identify an unauthorized vehicle, and a second video camera aimed after the toll station to photograph when the unauthorized vehicle has passed the toll station without paying a toll.

38. A video toll enforcement system comprising a plurality of toll-authorizing in-vehicle components each carried in a vehicle and configured for automatic payment of a vehicle toll as the vehicle drives past toll stations, and video imaging means including a video receiver located near a toll station and positioned to view incoming traffic, wherein each said toll-authorizing in-vehicle component includes means for providing a visually detectable indication, and the video imaging means further includes means for tracking traffic viewed by the video receiver to detect the visually detectable indication.

39. An in-vehicle component for an automatic toll collection system, such component comprising a processor including information storage and an operating program configured to debit a toll-money-available balance in said storage responsive to a toll collection signal received from a toll station, a transponder interfaced with said processor for receiving toll station communications and responding thereto with toll payment information and for generating a signal to said processor to debit of said toll-money-available balance in response to said received toll collection signal, and a beacon generator coupled to said processor for generating a beacon signal outside of the radio-frequency spectrum and representative of said debit made to said toll-money-available balance.

40. An in-vehicle component according to claim 39 wherein said beacon generator includes an optical radiator element for generating an optically detectable beacon signal.

41. An in vehicle component according to claim 39 wherein said beacon generator includes an optical radiator element for generating an infra-red beacon signal.

42. An in-vehicle component according to claim 39 wherein said processor includes an operating program for activating said beacon generator responsive to an activation signal received by said transponder.