Traffic sensor incorporating a video camera and method of operating same

1. A method of operating a traffic sensor to collect vehicular traffic data for a road, the traffic sensor having a radar module and an image module both contained in a traffic sensor enclosure, the method comprising:

a) operating the radar module to generate radar-based vehicle data regarding a plurality of vehicles passing a sensor field of view based on detection and measurement of the traffic on the road;

b) operating the image module to generate image data representing a plurality of images of the road and the traffic on the road;

c) determining if a triggering event has occurred;

d) transmitting the radar-based vehicle data to a remote location spaced from the traffic sensor and, if the triggering event is determined to have occurred, transmitting the image data to the remote location; and

e) if the triggering event is determined to have occurred, comparing the radar-based vehicle data with the image data at the remote location;

wherein the image module is a video camera and the image data is not transmitted to the remote location and is not compared with the radar-based vehicle data unless the triggering event is determined to have occurred.

2. The method as defined in claim 1 wherein step e) comprises providing both the radar-based vehicle data and the image data to a human operator for verification of the radar-based vehicle data using the image data.

3. The method as defined in claim 1 further comprising compressing the image data before transmitting the compressed image data to the remote location.

4. The method as defined in claim 3 further comprising, before step e), if the triggering event is determined to have occurred, combining the radar-based vehicle data and the compressed image data, transmitting the combined radar-based vehicle data and compressed image data to the remote location via a single channel, and then separating and separately displaying the radar-based vehicle data and the image data.

5. The method as defined in claim 1 further comprising reviewing the radar-based vehicle data at the remote location to determine if the triggering event has occurred, and, if the triggering event is determined to have occurred, sending an instruction signal to the traffic sensor to instruct the traffic sensor to transmit the image data to the remote location.

6. The method as defined in claim 1 further comprising controlling the frame rate of transmission of the image data to the remote location.

7. The method as defined in claim 1 wherein the triggering event is an instruction signal sent to the traffic sensor to instruct the traffic sensor to transmit the image data to the remote location.

8. The method as defined in claim 1 further comprising processing the radar-based vehicle data at the traffic sensor to determine if the triggering event has occurred, and, if the triggering event is determined to have occurred, transmitting the image data to the remote location.

9. The method as defined in claim 8 further comprising storing a plurality of trigger criteria, wherein the step of processing the radar-based vehicle data at the traffic sensor to determine if the triggering event has occurred comprises determining if an event has occurred satisfying any of the plurality of trigger criteria.

10. The method as defined in claim 3 , wherein the step of compressing the image data comprises compressing the image data in one of MPEG-2 and MPEG-4 format.

11. The method as defined in claim 1 , wherein the step of transmitting the radar-based vehicle data comprises transmitting the radar-based vehicle data and the image data to a remote location via TCP/IP protocol.

12. A traffic sensor for collecting vehicular traffic data for a road, the traffic sensor comprising:

a radar module for generating radar-based vehicle data regarding a plurality of vehicles passing the sensor field of view based on detection and measurement of traffic;

an image module for generating image data representing a plurality of images of the road and the traffic;

a communication link for transmitting both the radar-based vehicle data and the image data to a remote location spaced from the traffic sensor;

a processor for determining if a triggering event has occurred, wherein the processor is operable to control transmission of the image data to the remote location such that the image data is not transmitted to the remote location unless the triggering event is determined to have occurred; and

a traffic sensor enclosure for enclosing both the radar module and the image module.

13. The traffic sensor as defined in claim 12 wherein the image module comprises a video camera for generating the plurality of images.

14. The traffic sensor as defined in claim 13 wherein the traffic sensor enclosure comprises a window for providing the video camera with a sight field of view overlapping the sensor field of view.

15. The traffic sensor as defined in claim 12 further comprising an internal compression circuit for compressing the image data before transmitting the compressed image data to the remote location.

16. The traffic sensor as defined in claim 12 wherein the communication link comprises a single channel, and the traffic sensor further comprises a multiplexer for combining the radar-based vehicle data and the compressed image data for transmission to the remote location via the single channel.

17. The traffic sensor as defined in claim 12 wherein the triggering event is an instruction signal sent to the traffic sensor to instruct the traffic sensor to transmit the image data to the remote location.

18. The traffic sensor as defined in claim 12 wherein the processor is operable to process the radar-based vehicle data at the traffic sensor to determine if the triggering event has occurred.

19. The traffic sensor as defined in claim 18 further comprising a storage module for storing a plurality of trigger criteria, wherein the processor is operable to process the radar-based vehicle data at the traffic sensor to determine if the triggering event has occurred by determining if an event has occurred satisfying any of the plurality of trigger criteria stored in the storage module.

20. The traffic sensor as defined in claim 12 wherein the processor is further operable to control the frame rate of transmission of the image data to the remote location.

21. A method of operating a traffic sensor to collect vehicular traffic data for a road, the traffic sensor having a radar module and an image module both contained in a traffic sensor enclosure, the method comprising:

a) operating the radar module to generate radar-based vehicle data regarding a plurality of vehicles passing a sensor field of view based on detection and measurement of the traffic on the road;

b) operating the image module to generate image data representing a plurality of images of the road and the traffic on the road; and

c) comparing the radar-based vehicle data with the image data;

wherein step c) comprises providing both the radar-based vehicle data and the image data to a human operator for verification of the calibration of the traffic sensor using the radar-based vehicle data and the image data.

22. The method as defined in claim 21 wherein the radar-based vehicle data is verified in step c) to determine whether the traffic sensor is calibrated to detect vehicles passing through the sensor field of view.

23. The method as defined in claim 21 wherein the radar-based vehicle data is verified in step c) to determine whether the traffic sensor is calibrated such that the sensor field of view is centered on a lane of traffic.