Rectifying erroneous road traffic sensor data

• US 7,706,965 B2
• Filed: 09/28/2006
• Issued: 04/27/2010
• Est. Priority Date: 08/18/2006
• Status: Active Grant

• Current Assignee: Inrix Incorporated
• Original Assignee: Inrix Incorporated
• Inventors: England, James Allen, Downs, Oliver B., Barker, Alec, Chapman, Craig H.
• Primary Examiner(s): Beaulieu; Yonel
• Application Number:
  US11/540,342
• Publication Number:
  US 20080046165A1
• Time in Patent Office: 1,307 Days
• Field of Search: 701117-119, 701/200, 340/907, 340/910, 340/931
• US Class Current: 701/117
• CPC Class Codes: G08G 1/0104 Measuring and analyzing of parameters relative to traffic conditions

Abstract

Techniques are described for assessing road traffic conditions in various ways based on obtained traffic-related data, such as data samples from road traffic sensors (e.g., physical sensors that are near or embedded in the roads) and/or from vehicles and other mobile data sources traveling on the roads. The assessment of road traffic conditions based on obtained sensor data readings and/or other data samples may include various filtering and/or conditioning of the data samples, and various inferences and probabilistic determinations of traffic-related characteristics of interest. Assessing obtained data may further include determining traffic conditions (e.g., traffic flow and/or average traffic speed) for various portions of a road network in a particular geographic area, based at least in part on obtained data samples.

Claims

1. A computer-implemented method for facilitating travel on roads by providing reliable data readings for road traffic sensors associated with the roads in such a manner as to accurately reflect actual vehicle travel on the roads, the method comprising:

receiving indications of multiple road segments of one or more roads, each road segment having one or more associated road traffic sensors that provide data regarding speeds of vehicles traveling by the road traffic sensors; and

for each of at least some of the road traffic sensors, automatically providing reliable vehicle travel speed data for a recent period of time, by

receiving from the road traffic sensor multiple data readings that each include a reported speed of one or more vehicles traveling by the road traffic sensor at an associated time that is within the recent period of time;

determining a current data reading distribution for the road traffic sensor to reflect reported vehicle travel speeds during the recent period of time based on the received data readings;

determining an average historical data reading distribution for the road traffic sensor to reflect average vehicle travel speeds during one or more prior periods of time that correspond to the recent period of time, the average historical data reading distribution being based on multiple data readings received from the road traffic sensor during the one or more prior periods of time;

generating a comparison of the current and average historical data reading distributions for the road traffic sensor based at least in part on determining a statistical measure of entropy for each of the current and average historical data reading distributions and on determining a statistical measure of similarity between the current and average historical data reading distributions;

determining whether the road traffic sensor likely provided reliable data readings for the recent period of time based at least in part on whether the generated comparison indicates sufficient differences between the current and average historical data reading distributions for the traffic sensor to reflect a likely malfunction of the road traffic sensor; and

if the road traffic sensor is determined to not have likely provided reliable data readings for the recent period of time, estimating reliable vehicle speeds for the recent period of time for at least a portion of the road segment associated with the road traffic sensor in a manner that is not based on the received data readings for the recent period of time, and providing the estimated vehicle speeds for use as a replacement for the received data readings for the recent period of time,

so as to facilitate travel on the one or more roads by providing reliable data about vehicle travel.

2. The method of claim 1 further comprising, for each of one or more of the at least some road traffic sensors, determining a sensor health status for the road traffic sensor based at least in part on whether the road traffic sensor is determined to have likely provided reliable data readings for the recent period of time, and providing an indication of the determined sensor health status for the road traffic sensor.

3. The method of claim 1 wherein, for each of one or more of the at least some road traffic sensors, the estimating of the reliable vehicle speeds for the recent period of time for at least a portion of the road segment associated with the road traffic sensor is based on at least one of reported vehicle travel speeds for a second road segment that is related to the road segment associated with the road traffic sensor, of predictive information that reflects vehicle travel speeds predicted to occur on the road segment associated with the road traffic sensor during the recent period of time, and of historical average vehicle travel speeds for the road segment associated with the road traffic sensor.

4. The method of claim 1 wherein, for each of one or more of the at least some road traffic sensors, the determining of whether the road traffic sensor likely provided reliable data readings for the recent period of time is further based at least in part on an automated classification of likely reliability using the determined statistical measure of entropy for each of the current and average historical data reading distributions for the road traffic sensor and the determined statistical measure of similarity between the current and average historical data reading distributions for the road traffic sensor, the automated classification being performed by a neural network.

5. The method of claim 4 wherein, for each of one or more of the at least some road traffic sensors, the determining of whether the road traffic sensor likely provided reliable data readings for the recent period of time is further based in part on an indication of an operational status provided by the road traffic sensor and whether the road traffic sensor likely provided reliable data readings for a previous period of time.

6. The method of claim 5 wherein, for each of one or more of the at least some road traffic sensors, the one or more prior periods of time that correspond to the recent period of time include multiple periods of time that are selected to match at least one of a day-of-week associated with the recent period of time and a time-of-day associated with the recent period of time.

7. The method of claim 1 wherein each of the at least some road traffic sensors is one of a loop sensor embedded in a road, a motion sensor installed adjacent to a road, a radar ranging device installed adjacent to a road, and a radio frequency identifier device installed adjacent to a road, and wherein each of the at least some road traffic sensors is configured to measure speeds of vehicles traveling by the road traffic sensor.

8. The method of claim 1 wherein, for each of one or more of the at least some road traffic sensors, at least some of the multiple data readings received from the road traffic sensor each further include a reported number of vehicles traveling by the road traffic sensor during a period of time and/or an indication of an operational status of the road traffic sensor.

9. The method of claim 1 wherein, for each of one or more of the at least some road traffic sensors, the determined statistical measure of similarity between the current and average historical data reading distributions is based on calculation of a Kullback-Leibler divergence between the current and average historical data reading distributions.

10. The method of claim 1 wherein the recent period of time is a portion of a day, and wherein the automatic providing of the reliable vehicle travel speed data for each of one or more of the at least some road traffic sensors is performed multiple times per day in order to provide reliable vehicle travel speed data readings for each of successive periods of time throughout the day.

11. A computer-implemented method for providing reliable data readings from road traffic sensors regarding traffic conditions on one or more roads, the method comprising:

for each of one or more road traffic sensors that each have an associated location on an associated road, receiving information about multiple data readings taken by the road traffic sensor during a period of time, each data reading having an associated time and reflecting one or more measurements of traffic conditions at the associated time at the associated location of the associated road for the road traffic sensor; and

for each of the one or more road traffic sensors,

automatically determining whether the multiple data readings taken by the road traffic sensor during the period of time are likely to be unreliable, the determining being based at least in part on an automated comparison of information about at least some of those multiple data readings to information about multiple other data readings previously taken by the road traffic sensor;

if the multiple data readings taken by the road traffic sensor during the period of time are not determined to be likely to be unreliable, providing an indication to use those multiple data readings in representing actual traffic conditions at the associated location of the associated road for the road traffic sensor during the period of time; and

if the multiple data readings taken by the road traffic sensor during the period of time are determined to be likely to be unreliable, automatically providing an indication to use other estimated data in place of those multiple data readings in representing the actual traffic conditions at the associated location of the associated road for the road traffic sensor during the period of time, the other estimated data being based at least in part on other road traffic data that is related to those multiple data readings,

so that travel on one or more roads is facilitated by automatically eliminating road traffic sensor data readings that are likely to be unreliable.

12. The method of claim 11 further comprising, for each of at least one of the one or more road traffic sensors, determining a sensor health status for the road traffic sensor for the period of time based at least in part on the comparison of information about the at least some of the multiple data readings to the information about the multiple other data readings previously taken by the road traffic sensor, and providing an indication of the determined sensor health status for the road traffic sensor.

13. The method of claim 12 wherein, after determining that the sensor health status for a road traffic sensor for a period of time is unhealthy, automatic determining during one or more later periods of time of whether data readings taken by the road traffic sensor during those later periods of time are likely to be unreliable is further based at least in part on the determined unhealthy status for the period of time.

14. The method of claim 11 wherein, for each of at least one of the one or more road traffic sensors, the automatic determining of whether the multiple data readings taken by the road traffic sensor during the period of time are likely to be unreliable includes determining a current data reading distribution for the road traffic sensor to reflect traffic conditions during the period of time based on the at least some multiple data readings for the road traffic sensor, and determining an average historical data reading distribution to reflect average traffic conditions during one or more prior periods of time based on the multiple other data readings previously taken by the road traffic sensor.

15. The method of claim 14 wherein, for each of the at least one road traffic sensors, the comparison of the information about the at least some multiple data readings to the information about the multiple other data readings previously taken by the road traffic sensor includes comparing statistical measures of information entropy for the current and average historical data reading distributions.

16. The method of claim 14 wherein, for each of the at least one road traffic sensors, the comparison of the information about the at least some multiple data readings to the information about the multiple other data readings previously taken by the road traffic sensor includes determining a statistical measure of similarity between the current and average historical data reading distributions.

17. The method of claim 16 wherein, for each of the at least one road traffic sensors, the determined statistical measure of similarity between the current and average data reading distributions is based on a calculation of a Kullback-Leibler divergence.

18. The method of claim 11 wherein, for each of at least one of the one or more road traffic sensors, the comparison of the information about the at least some multiple data readings to the information about the multiple other data readings previously taken by the road traffic sensor further includes classifying the information about the at least some multiple data readings.

19. The method of claim 18 wherein, for each of the at least one road traffic sensors, the classifying is performed by at least one of a neural network, a decision tree, and a Bayesian classifier.

20. The method of claim 11 wherein, for each of at least one of the one or more road traffic sensors, the other estimated data to be used in place of the multiple data readings taken by the road traffic sensor during the period of time is further based at least in part on a combination of at least some other road traffic sensor data readings that are related to those multiple data readings.

21. The method of claim 20 wherein, for one of the at least one road traffic sensors, the at least some other road traffic sensor data readings include data readings taken by one or more nearby road traffic sensors that are located on the associated road for the road traffic sensor.

22. The method of claim 21 wherein the one road traffic sensor is one of multiple traffic sensors associated with one of multiple road segments of the road associated with the one road traffic sensor, and wherein the one or more nearby road traffic sensors are part of the one road segment.

23. The method of claim 21 wherein the one road traffic sensor is one of multiple traffic sensors associated with one of multiple road segments of the road associated with the one road traffic sensor, and wherein the one or more nearby road traffic sensors are part of one or more other road segments adjacent to the one road segment.

24. The method of claim 20 wherein, for one of the at least one road traffic sensors, the at least some other road traffic sensor data readings include data readings taken by the road traffic sensor during one or more prior periods of time, the one or more prior periods of time selected at least in part to match a time category associated with the period of time.

25. The method of claim 20 wherein, for each of at least one of the one or more road traffic sensors, the at least some other road traffic sensor data readings include data samples from mobile data sources that are traveling on the associated road near the associated location for the road traffic sensor during the period of time.

26. The method of claim 11 wherein, for each of at least one of the one or more road traffic sensors, the other estimated data to be used in place of the multiple data readings taken by the road traffic sensor during the period of time is further based at least in part on predictive information that reflects traffic conditions predicted to occur during the period of time at the associated location of the associated road for the road traffic sensor, the predictive information being generated shortly before the period of time based in part on current traffic condition data at a time of generating the predictive information for the period of time.

27. The method of claim 11 wherein, for each of at least one of the one or more road traffic sensors, the other estimated data to be used in place of the multiple data readings taken by the road traffic sensor during the period of time is further based at least in part on forecast information that reflects traffic conditions forecasted to occur during the period of time at the associated location of the associated road for the road traffic sensor, the forecast information being generated sufficiently before the period of time that current traffic condition data at a time of generating the forecast information is not used as part of generating the forecast information for the period of time.

28. The method of claim 11 further comprising, for one of the road traffic sensors, failing to receive information about at least some missing data readings taken by the one road traffic sensor during a period of time, and automatically providing an indication to use other estimated data in place of the missing data readings in representing actual traffic conditions at the associated location of the associated road for the one road traffic sensor during the period of time.

29. The method of claim 11 further comprising, for each of at least one of the one or more road traffic sensors, automatically determining an operational state of the road traffic sensor based at least in part on whether the multiple data readings taken by the road traffic sensor during the period of time are determined to be likely to be unreliable, and providing an indication of the operational state.

30. The method of claim 11 wherein, for each of at least one of the one or more road traffic sensors, the automatic determining of whether the multiple data readings taken by the road traffic sensor during the period of time are likely to be unreliable is further based on multiple of a day-of-week associated with the period of time, a time-of-day associated with the period of time, an indication of an operational status provided by the road traffic sensor, whether the road traffic sensor likely provided reliable data readings during one or more previous periods of time, and an absence of data readings ordinarily taken by the road traffic sensor.

31. The method of claim 11 wherein, for each of at least one of the one or more road traffic sensors, the multiple data readings for the road traffic sensor each include a reported speed of vehicles traveling by the road traffic sensor at the associated time for the data reading.

32. The method of claim 11 wherein, for each of at least one of the one or more road traffic sensors, the multiple data readings for the road traffic sensor each include a reported quantity of vehicles traveling by the road traffic sensor over a period of time and/or an indication of an operational status of the road traffic sensor.

33. The method of claim 11 further comprising, for each of at least one of the one or more road traffic sensors, providing reliable data readings for the road traffic sensor to one or more traffic data clients, the reliable data readings including at least some of the multiple data readings and/or the other estimated data.

34. The method of claim 11 wherein each of at least some of the one or more road traffic sensors includes at least one of a loop sensor embedded in the associated road for the road traffic sensor, a motion sensor installed adjacent to the associated road for the road traffic sensor, a radar ranging device installed adjacent to the associated road for the road traffic sensor, and a radio frequency identifier device installed adjacent to the associated road for the road traffic sensor, and wherein each of the at least some road traffic sensors is configured to measure traffic conditions at the associated location of the associated road for the road traffic sensor.

35. The method of claim 11 wherein the method is performed multiple times per day in order to provide reliable data readings for at least some of the one or more road traffic sensors for each of multiple portions of the day.

36. A computer-readable medium whose contents enable a computing device to provide reliable data readings from a road traffic sensor regarding traffic conditions on a road, by performing a method comprising:

receiving multiple data readings generated by a traffic sensor associated with a road that each reflect one or more measurements of traffic conditions on the associated road at an associated time;

automatically determining current reliability of the traffic sensor based at least in part on comparing information about at least some of the multiple data readings to information about multiple other data readings previously generated by the traffic sensor; and

providing an indication of the determined current reliability of the traffic sensor for use in facilitating travel on the road, so that data readings generated by a currently unreliable traffic sensor are not used to represent actual traffic conditions.

37. The computer-readable medium of claim 36 wherein the information about the at least some multiple data readings includes a first data reading distribution based on the at least some multiple data readings, and wherein the information about the multiple other data readings previously generated by the traffic sensor includes a second data reading distribution based on the multiple other data readings previously generated by the traffic sensor.

38. The computer-readable medium of claim 37 wherein the comparing of the information about the at least some multiple data readings to the information about the multiple other data readings previously generated by the traffic sensor includes determining a statistical measure of similarity between the first and second data reading distributions and determining a statistical measure of entropy for each of the first and second data reading distributions.

39. The computer-readable medium of claim 36 wherein the determining of the current reliability of the traffic sensor is further based at least in part on classifying the information about the at least some multiple data readings.

40. The computer-readable medium of claim 36 wherein the associated times of the multiple data readings are during a current period of time, and wherein the determining of the current reliability of the traffic sensor is for the current period of time and is further based at least in part on an automatic determination of reliability of the traffic sensor for each of one or more prior periods of time.

41. The computer-readable medium of claim 36 wherein the method further comprises, if the determined current reliability of the traffic sensor is determined to be reliable, providing at least some of the multiple data readings for use in representing actual traffic conditions on the associated road at the associated time, and if the determined current reliability of the traffic sensor is determined to not be reliable, providing other estimated data for use in representing actual traffic conditions on the associated road at the associated time.

42. The computer-readable medium of claim 36 wherein the computer-readable medium is at least one of a memory of a computing device and of a data transmission medium transmitting a generated data signal containing the contents.

43. The computer-readable medium of claim 36 wherein the contents are instructions that when executed cause the computing device to perform the method.

44. A computing device configured to provide reliable data from a traffic sensor regarding traffic conditions on an associated road, comprising:

a memory;

a first module configured to, after receiving information generated by a traffic sensor associated with a road that reflects one or more measurements of traffic conditions on the associated road at multiple distinct times during a period of time, automatically determine reliability of the generated information in representing actual traffic conditions on the associated road during the period of time based at least in part on comparing the generated information to other information previously generated by the traffic sensor to reflect one or more measurements of traffic conditions on the associated road for one or more other periods of time; and

a second module configured to provide an indication of the determination of the reliability of the generated information in representing actual traffic conditions on the associated road during the period of time, so as to facilitate travel on the associated road via use of information that reliably represents actual traffic conditions on the associated road.

45. The computing device of claim 44 wherein the automatic determining of the reliability of the generated information in representing actual traffic conditions on the associated road during the period of time further includes determining whether the generated information reflects a minimum number of measurements to provide a sufficient degree of reliability for the period of time, and wherein the comparing of the generated information to other information is performed only if the generated information reflects the minimum number of measurements.

46. The computing device of claim 44 wherein, if the generated information does not reflect the minimum number of measurements to provide a sufficient degree of reliability for the period of time, the generated information is replaced with other estimated data based at least in part on other road traffic data that is related to a portion of the road corresponding to the traffic sensor, and wherein the provided indication of the determination of the reliability of the generated information includes providing an indication of the other estimated data.

47. The computing device of claim 44 wherein the provided indication of the determination of the reliability of the generated information includes an indication to use the generated information to represent actual vehicle travel of the road during the period of time if the generated information is determined to be reliable, and includes an indication to use other estimated data to represent actual vehicle travel of the road during the period of time if the generated information is not determined to be reliable.

48. The computing device of claim 44 wherein the first and second modules include software instructions for execution in the memory.