System and method for detecting traffic anomalies

• US 6,177,885 B1
• Filed: 11/03/1998
• Issued: 01/23/2001
• Est. Priority Date: 11/03/1998
• Status: Expired due to Fees

• Current Assignee: ESCO Electronics Corporation
• Original Assignee: ESCO Electronics Corporation
• Inventors: Weil, Roark D., Wootton, John R., Garcia-Ortiz, Asdrubal
• Primary Examiner(s): POPE, DARYL C
• Application Number:
  US09/185,321
• Time in Patent Office: 812 Days
• Field of Search: 340/933, 340/934, 340/937, 701/117, 701/118
• US Class Current: 701/117
• CPC Class Codes: G08G 1/0104 Measuring and analyzing of parameters relative to traffic conditions

Abstract

A traffic incident detection system (10) includes both the collection and analysis of traffic data and employs a time-indexed traffic anomaly detection algorithm which partitions time into categories of “type of day,” and “time of day”. Using this partition, a fuzzy neuromorphic, unsupervised learning algorithm calibrates fuzzy sets as “normal” and “abnormal” for a plurality of traffic descriptors. Fuzzy composition techniques are used, on a per traffic lane basis, to combine multiple traffic descriptors in order to determine membership in a “normal” or “abnormal” lane status. Each lane status is then combined to determine the overall status of a road segment. Initial training of the algorithm occurs during the first few weeks after a sensor (12) is installed. On-line background training continues thereafter to continually tune and track seasonal changes affecting system performance.

Claims

1. A traffic monitoring system monitoring traffic flow on a specific roadway section comprising:

an active fixed position sensor obtaining measurements of passive, non-sensor bearing-vehicles moving over a roadway; and

,

a processor co-located with said sensor and processing said measurements in accordance with an algorithm which takes into account traffic volume, traffic speed, roadway occupancy, and vehicle headway to determine, in accordance with an established set of temporal and spatial evaluation criteria if the traffic condition on the roadway, at any given time, is normal or abnormal, an abnormal condition signifying a traffic incident has occurred, said algorithm employing fuzzy logic to determine whether or not traffic conditions are normal or abnormal, the fuzzy logic employed evaluating at least the day of the week, the time of the day, the season of the year, and the specialness, if any, of the day, the preceding day, or the following day.

2. The system of claim 1 further including a base station to which an abnormal roadway condition is reported by said processor for said abnormality to be investigated.

3. The system of claim 1 wherein said roadway includes a plurality of traffic lanes each of which is observed by said sensor, and said processor makes a separate evaluation as to the normal or abnormal condition of each lane as well as the condition of the entire segment of roadway observable by said sensor.

4. The system of claim 3 further including a plurality of sensors, one for each lane of said roadway.

5. The system of claim 1 wherein said algorithm further takes into account the time of day and day of the week at which traffic is being observed including special event days.

6. The system of claim 1 wherein said sensor is a non-imaging sensor.

7. The system of claim 1 wherein said sensor is an imaging sensor.

8. A method of detecting traffic incidents occurring on a roadway comprising:

sensing the presence and movement of passive, non-signal-transmitting vehicular traffic moving over the roadway, the presence and movement being treated as data; and

,

processing said data in-situ to determine if traffic conditions on the roadway are normal or abnormal, processing a measurement including evaluating a local traffic related factor in conjunction with at least one time factor, and further in accordance with an established set of evaluation criteria as a result of which an a-priori traffic related factor which is present at one time may indicate traffic conditions on the roadway are normal, but at another time abnormal, an abnormal condition signifying a traffic incident has occurred, said processing including the use of fuzzy logic to determine whether or not traffic conditions are normal or abnormal, the fuzzy logic employed evaluating at least the day of the week, the time of the day, the season of the year, and the specialness, if any, of the day, the preceding day, or the following day.

9. The method of claim 8 further including notifying a base station if an abnormal condition is determined for said condition to be investigated.

10. The method of claim 8 wherein processing said measurements includes employing an algorithm which takes into account local traffic flow over the roadway.

11. The method of claim 10 wherein said algorithm further takes into account one or more of the following factors:

traffic speed, roadway occupancy, and vehicle headway.

12. The method of claim 10 wherein said roadway has a plurality of traffic lanes and said algorithm separately evaluates the traffic on each lane and determines if the traffic is normal or abnormal.

13. The method of claim 12 wherein said algorithm makes an overall determination as to whether the traffic flow over the segment of roadway for which measurements are obtained is normal or abnormal based upon the various factors.

14. A method of evaluating a segment of roadway and traffic moving thereover to determine if traffic flow over the roadway is normal, or if an incident affecting traffic flow has occurred, comprising:

obtaining an image of the roadway segment and the traffic moving thereover;

processing said image in-situ and deriving therefrom at least one factor relating to movement of traffic over the roadway;

classifying the time at which the image is obtained in accordance with a predetermined set of criteria; and

evaluating said traffic factor in conjunction with said time classification to determine if traffic conditions are normal or abnormal, an abnormal determination signifying a traffic incident has occurred, evaluating said traffic factor including the use of fuzzy logic to determine whether or not traffic conditions are normal or abnormal, the fuzzy logic employed evaluating at least the day of the week, the time of the day, the season of the year, and the specialness, if any, of the day, the preceding day, or the following day.

15. The method of claim 14 wherein said traffic factor includes at least one of the following:

traffic volume, traffic speed, traffic occupancy of the roadway, and traffic headway.

16. The method of claim 15 wherein both said time of day and said day of week classifications are separately combined with a traffic factor in making said determination.

17. The method of claim 16 wherein a separate evaluation is made for each of said traffic factors and said evaluations are then combined to form an overall traffic evaluation.

18. The method of claim 17 wherein each separate factor evaluation is classified as either normal or abnormal and the overall traffic evaluation is normal if all of the separate factor evaluations are normal, but abnormal if any one of the separate factor evaluations is abnormal.

19. The method of claim 18 wherein said roadway includes a plurality of traffic lanes and a separate evaluation, including both of the time classifications and all of the aforesaid traffic factors, is made for each lane.

20. The method of claim 19 including providing a traffic incident indication to a base station if an abnormal condition is signified.

21. The method of claim 20 including providing video images of the roadway to the base station together with the abnormal indication.

22. A system for detecting road traffic flow anomalies comprising:

an active, fixed position sensor mounted as to sense the presence and movement of passive, non-sensor-bearing vehicles and collecting this information as data;

a processor, co-located with said sensor, for computing traffic flow parameter values from traffic flow data; and

,

a method for categorizing traffic flow from said traffic flow parameter values, said method including the use of fuzzy logic to determine whether or not traffic conditions are normal or abnormal, the fuzzy logic employed evaluating at least the day of the week, the time of the day, the season of the year, and the specialness, if any, of the day, the preceding day, or the following day.

23. The system of claim 22 wherein said sensor is an imaging sensor.

24. The system of claim 23 wherein said imaging sensor is a CCD video camera.

25. The system of claim 23 wherein said sensor is an infrared video camera.

26. The system of claim 22 wherein said sensor is a non-imaging sensor.

27. The system of claim 26 wherein said non-imaging sensor is a photo detector.

28. The system of claim 26 wherein said non-imaging sensor is a microwave sensor.

29. The system of claim 26 wherein said non-imaging sensor is an infrared sensor.

30. The system of claim 26 wherein said non-imaging sensor is an acoustic sensor.

31. The system of claim 22 wherein said sensor provides coverage for a single lane of traffic.

32. The system of claim 31 wherein including a plurality of sensors, one for each lane of traffic.

33. The system of claim 32 further including a plurality of processors, one for each said sensor, and used to compute the traffic flow parameters of the lane covered by said sensor.

34. The system of claim 22 wherein said sensor provides coverage for a plurality of traffic lanes on said road.

35. The system of claim 22 wherein said processor is a general purpose processor.

36. The system of claim 22 wherein said processor is a digital signal processor.

37. The system of claim 22 wherein said traffic flow parameters include volume, speed, density, occupancy, link travel time, and headway.

38. The system of claim 37 wherein said traffic flow parameter values are determined for each lane of traffic covered by said sensor.

39. The system of claim 38 wherein said traffic flow parameter values are updated every time a vehicle passes by said sensor.

40. The system of claim 39 wherein said traffic flow parameter values are integrated over a period of time to generate a time-dependent measure of traffic flow for each said parameter.

41. The system of claim 40 further including use of the fuzzy logic techniques to map said time-of-the-day to a fuzzy time-of-the-day set.

42. The system of claim 41 wherein said fuzzy time-of-the-day set comprises Early Morning, Early Morning Rush, Mid-Morning Rush, Late Morning Rush, Late Morning, Lunch Time, Mid Afternoon, Early Evening, Early Evening Rush, Late Evening Rush, and Late Evening.

43. The system of claim 41 further including the use of fuzzy logic techniques to map said day-of-the-week to a fuzzy day-of-the-week set.

44. The system of claim 43 wherein said fuzzy day-of-the-week set comprises Work Day, Work Day Preceding a Holiday, Holiday and End of Holiday.

45. The system of claim 43 further including the use of a fuzzy rule base to map said degree-of-specialness and said day-of-the-week into said fuzzy day-of-the-week set.

46. The system of claim 40 further including a plurality of learning elements in said method, one for each traffic flow measure, which combine each said traffic flow measure with said time-of-the-day and said day-of-the-week to categorize each said traffic flow measure as Normal or Abnormal.

47. The system of claim 46 wherein said learning element is trained to recognize normal traffic flow.

48. The system of claim 47 wherein said training takes place when said sensor is first placed into service.

49. The system of claim 47 wherein periodic training takes place to accommodate seasonal variations in traffic flow.

50. The system of claim 47 wherein said training takes place in an unsupervised manner.

51. The system of claim 50 wherein said unsupervised training is done using neural network techniques.

52. The system of claim 47 wherein said training results in a plurality of discriminant functions, one for each traffic flow parameter.

53. The system of claim 52 wherein said discriminant functions are fuzzy membership functions.

54. The system of claim 52 further including the combination of the traffic flow parameter value categorizations into a per-lane traffic flow categorization.

55. The system of claim 54 wherein fuzzy logic techniques are used to categorize said lane traffic flow as Normal or Abnormal.

56. The system of claim 54 further including the combination of the per-lane traffic flow categorizations into a road traffic flow categorization.

57. The system of claim 56 wherein fuzzy logic techniques are used to categorize the road traffic flow as Normal, Low Level Anomaly, Severe Anomaly, or Critical Anomaly.

58. The system of claim 22 further including a communication channel over which an indication of abnormal traffic flow is sent to a traffic control center.

59. The system of claim 58 wherein said indication consists of an alarm.

60. The system of claim 59 wherein said alarm is an audible alarm.

61. The system of claim 59 wherein said alarm is a visual alarm.

62. The system of claim 59 further including the transmission of an image of the roadway.