Dynamic timing adjustment in an electronic toll collection system

• US 20070008184A1
• Filed: 07/07/2005
• Published: 01/11/2007
• Est. Priority Date: 07/07/2005
• Status: Active Grant

• Current Assignee: Mark IV Industries Corporation
• Original Assignee: Mark IV Industries Corporation
• Inventors: Tong, Roger, Terrier, Daniel, Tang, Wai-Cheung, Capper, Martin, Ho, Thua
• Granted Patent: US 7,385,525 B2
• Time in Patent Office: Days
• US Class Current: 340/941
• CPC Class Codes: G07B 15/063 using wireless information transmission between the vehicle and a fixed station identification of vehicles G08G
• CPC Class Codes: G08G 1/015 with provision for distinguishing between two or more types of vehicles, e.g. between motor-cars and cycles
• CPC Class Codes: G08G 1/042 using inductive or magnetic detectors

Abstract

An electronic toll collection system with dynamically adjusted timing for operation of one or more subsystems. The timing is dynamically adjusted based upon the prevailing traffic speed for the roadway. The roadway traffic speed is determined based upon direct measurements of traffic speed by external equipment or based upon a variable correlated with traffic speed. The variable may include the average number of handshakes per transponder over an estimation period. The subsystem may include a vehicle position determination system, an enforcement system, a loop detection system, or other such subsystems.

Claims

1. A vehicle position determination system for determining a position of a moving vehicle having a transponder in a multi-lane roadway, comprising:

two or more antennas having partially overlapped coverage areas, each for transmitting an interrogation signal and receiving a response signal from the transponder;

a reader for receiving said response signals from said antennas, said reader including

a position determination module for determining the position of the moving vehicle based upon said response signals received by said two or more antennas, wherein said determination is made on expiry of a time period, and

a dynamic timing module for determining a current traffic speed associated with the multi-lane roadway and for setting said time period based upon said current traffic speed.

2. The vehicle position determination system claimed in claim 1, wherein said current traffic speed comprises a variable correlated to traffic speed, and wherein said dynamic timing module measures said variable correlated to traffic speed.

3. The vehicle position determination system claimed in claim 2, wherein said variable correlated to traffic speed comprises an average number of response signals per transponder while in said coverage areas.

4. The vehicle position determination system claimed in claim 3, wherein said dynamic timing module includes a handshake counting module for counting response signals from each transponder entering said coverage areas over an estimation period and a time period selection module for calculating said average number of response signals per transponder and selecting said time period.

5. The vehicle position determination system claimed in claim 4, wherein said time period selection module calculates said average number of response signals per transponder on a per antenna basis.

6. The vehicle position determination system claimed in claim 5, wherein said antennas include at least two lane-centred antennas and at least one between-lane antenna, and wherein said time period selection module calculates said average with respect to said lane-centred antennas.

7. The vehicle position determination system claimed in claim 5, wherein said reader further includes a component for counting transactions per antenna over said estimation period, and wherein said time period selection module selects said time period based upon said average number of response signals per transponder calculated with respect to an antenna associated with the highest number of transactions.

8. The vehicle position determination system claimed in claim 2, wherein said dynamic timing module sets said time period based upon said average number of response signals.

9. The vehicle position determination system claimed in claim 8, wherein said dynamic timing module sets said calculated time period as a current time period for use by said position determination module if said calculated time period differs from a previous time period by more than a threshold amount.

10. The vehicle position determination system claimed in claim 1, wherein dynamic timing module includes an input for receiving measured current traffic speed data from an external source.

11. A method of determining a position of a moving vehicle having a transponder in a multi-lane roadway, the method comprising the steps of:

measuring a current traffic speed associated with the multi-lane roadway;

setting a time period based upon said current traffic speed;

exchanging communications with the transponder through two or more antennas having partially overlapped coverage areas, wherein exchanging communications includes transmitting an interrogation signal and receiving a response signal from the transponder; and

determining the position of the moving vehicle based upon said response signals received by said two or more antennas, wherein said determination is made on expiry of the time period.

12. The method claimed in claim 11, wherein said current traffic speed comprises a variable correlated to traffic speed, and wherein said step of measuring comprises measuring said variable correlated to traffic speed.

13. The method claimed in claim 12, wherein said variable correlated to traffic speed comprises an average number of response signals per transponder while in said coverage areas.

14. The method claimed in claim 13, wherein said step of measuring includes counting response signals from each transponder entering said coverage areas over an estimation period and determining said average number of response signals per transponder.

15. The method claimed in claim 14, wherein said step of determining includes calculating said average number of response signals per transponder on a per antenna basis.

16. The method claimed in claim 15, wherein said antennas include at least two lane-centred antennas and at least one between-lane antenna, and wherein said step of calculating is performed only with respect to said lane-centred antennas.

17. The method claimed in claim 15, further including a step of counting transactions per antenna over said estimation period, and wherein said step of setting said time period is based upon said average number of response signals per transponder calculated with respect to an antenna associated with the highest number of transactions.

18. The method claimed in claim 12, wherein said step of setting includes calculating said time period based upon said average number of response signals.

19. The method claimed in claim 18, wherein said step of setting further includes setting said calculated time period as a current time period for use in said step of determining if said calculated time period differs from a previous time period by more than a threshold amount.

20. The method claimed in claim 11, wherein said step of measuring includes receiving measured current traffic speed data from an external source.

21. An electronic toll collection system for conducting transactions with a moving vehicle having a transponder travelling on a roadway, the electronic toll collection system comprising:

at least one subsystem having a trigger component for triggering operation of the subsystem based upon a time period; and

a dynamic timing module for determining a current traffic speed associated with the roadway and for setting said time period based upon said current traffic speed.

22. The electronic toll collection system claimed in claim 21, wherein said subsystem comprises a vehicle position determination system including

two or more antennas having partially overlapped coverage areas, each for transmitting an interrogation signal and receiving a response signal from the transponder;

and

a reader for receiving said response signals from said antennas, said reader including a position determination module for determining the position of the moving vehicle based upon said response signals received by said two or more antennas, wherein said determination is made on expiry of said time period.

23. The electronic toll collection system claimed in claim 21, wherein said current traffic speed comprises a variable correlated to traffic speed, and wherein said dynamic timing module measures said variable correlated to traffic speed.

24. The electronic toll collection system claimed in claim 23, wherein said variable correlated to traffic speed comprises an average number of response signals per transponder while in an antenna coverage area.

25. The electronic toll collection system claimed in claim 24, wherein said dynamic timing module includes a handshake counting module for counting response signals from each transponder entering said coverage area over an estimation period and a time period selection module for calculating said average number of response signals per transponder and selecting said time period.

26. The electronic toll collection system claimed in claim 21, wherein dynamic timing module includes an input for receiving measured current traffic speed data from an external source.

27. The electronic toll collection system claimed in claim 21, wherein said subsystem comprises a loop detection system having at least one in-ground loop antenna and a loop detector for counting the number of axles on the moving vehicle and determining a vehicle class, and wherein said determination is based, at least in part, upon whether said time period elapses between the detection of axles.

28. The electronic toll collection system claimed in claim 21, wherein said subsystem comprises an enforcement system including at least one camera for capturing an image of the moving vehicle, and wherein said image is captured on expiry of said time period.

29. A method of dynamically adjusting timing within an electronic toll collection system for conducting transactions with a moving vehicle having a transponder travelling in a roadway, the method comprising the steps of:

measuring a current traffic speed associated with the roadway;

setting a time period based upon said current traffic speed; and

triggering operation of a subsystem of the electronic toll collection system upon expiry of said time period.

30. The method claimed in claim 29, wherein said subsystem includes a vehicle position determination system, wherein said method further includes a step of exchanging communications with the transponder through two or more antennas having partially overlapped coverage areas, wherein exchanging communications includes transmitting an interrogation signal and receiving a response signal from the transponder, and wherein said step of triggering includes determining the position of the moving vehicle based upon said response signals received by said two or more antennas, wherein said determination is made on expiry of the time period.

31. The method claimed in claim 29, wherein said current traffic speed comprises a variable correlated to traffic speed, and wherein said step of measuring comprises measuring said variable correlated to traffic speed.

32. The method claimed in claim 31, wherein said variable correlated to traffic speed comprises an average number of response signals per transponder while in a coverage area.

33. The method claimed in claim 32, wherein said step of setting includes calculating said time period based upon said average number of response signals.

34. The method claimed in claim 29, wherein said step of measuring includes receiving measured current traffic speed data from an external source.

35. The method claimed in claim 29, wherein said subsystem includes an enforcement camera for capturing an image of the moving vehicle, and wherein said step of triggering includes capturing said image with said enforcement camera.

36. The method claimed in claim 29, wherein said subsystem includes a loop detection system, wherein the method includes steps of counting the number of axles on the moving vehicle and determining a vehicle class, and wherein said step of determining is based at least in part upon whether said time period expires between detection of axles.