Assessing road traffic flow conditions using data obtained from mobile data sources

• US 7,831,380 B2
• Filed: 05/22/2006
• Issued: 11/09/2010
• Est. Priority Date: 03/03/2006
• Status: Active Grant

• Current Assignee: Inrix Incorporated
• Original Assignee: Inrix Incorporated
• Inventors: Downs, Oliver B., Chapman, Craig H.
• Primary Examiner(s): MANCHO, RONNIE M
• Application Number:
  US11/438,822
• Publication Number:
  US 20070208494A1
• Time in Patent Office: 1,632 Days
• Field of Search: 701/117, 701/119, 701/213, 701/200, 701/118, 340/995.13, 340/933, 340/907, 340/910, 340/931, 340/990, 340/995, 342/357.13
• US Class Current: 701/118
• 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 vehicles and other mobile data sources traveling on the roads, as well as in some situations data from one or more other sources (such as physical sensors near to or embedded in the roads). The assessment of road traffic conditions based on obtained data samples may include various filtering and/or conditioning of the data samples, and various inferences and probabilistic determinations of traffic-related characteristics from the data samples. In some situations, the inferences based on the data samples includes repeatedly determining traffic flow characteristics for road segments of interest during periods of time, such as to determine traffic volume and/or average occupancy of the road.

Claims

1. A computer-implemented method for determining estimated traffic flow information for roads based on data samples that are reported by vehicles traveling on the roads and that include information regarding the travel of the vehicles, the method comprising:

receiving indications of multiple road segments of one or more roads;

generating probability distributions that indicate, for each of multiple distinct observed quantities of vehicles on a road segment during a period of time, probabilities for arrival rate volumes of vehicles at the road segment given the observed quantity of vehicles; and

for each of multiple periods of time,

receiving information related to current traffic conditions of the multiple road segments during the period of time, the received information including a plurality of data samples for the period of time that each are reported from one of multiple vehicles and reflect a reported speed of the one vehicle at a reported location on one of the road segments at a reported time during the period of time, the multiple vehicles being a subset of all vehicles traveling on the road segments during the period of time, the received information further including a plurality of additional data samples for the period of time that each are reported from one of multiple traffic sensors monitoring the multiple road segments and reflect a reported speed based on one or more speed readings for one or more vehicles at a location on one of the road segments for one or more reported times during the period of time;

for each of the multiple road segments, automatically estimating traffic flow information of all vehicles traveling on the road segment during the period of time, the automatic estimating of the traffic flow information being performed by one or more programmed computer systems and including,

identifying a group of multiple data samples for the road segment for the period of time, the multiple data samples being from at least one of the plurality of data samples and the plurality of additional data samples;

determining a quantity of vehicles to which the data samples of the group correspond, the corresponding vehicles being a subset of all the vehicles traveling on the road segment during the period of time;

determining a most probable traffic arrival rate volume at the road segment of all the vehicles traveling on the road segment during the period of time, the determining of the traffic arrival rate volume being based at least in part on the generated probability distribution for the determined quantity of vehicles that reported the data samples of the group;

determining a most probable traffic density for the road segment so as to represent a total quantity per unit of distance of all the vehicles traveling on the road segment during the period of time, the determining of the traffic density being based at least in part on the determined traffic arrival rate volume for the road segment during the period of time; and

determining a most probable percentage traffic occupancy of at least one point on the road segment by all the vehicles traveling on the road segment during the period of time, the determining of the percentage traffic occupancy being based at least in part on the determined traffic density; and

using at least some of the determined traffic arrival rate volumes, traffic densities, and percentage traffic occupancies for the period of time to facilitate future travel on the one or more roads,

so that estimated traffic flow information is determined for road segments based on data samples reflecting actual vehicle travel on the road segments.

2. The method of claim 1 wherein, for each of at least one of the periods of time and each of at least one of the road segments, the identified group of multiple data samples for the road segment for the period of time includes multiple data samples from the plurality of data samples for the period of time whose reported locations are on the road segment and includes multiple data samples from the plurality of additional data samples for the period of time whose locations are on the road segment, and wherein the estimating of the traffic flow information of all the vehicles traveling on the road segment during the period of time includes generating an estimated average traffic speed of all the vehicles traveling on the road segment during the period of time based at least in part on the reported speeds of the data samples of the group.

3. The method of claim 2 wherein, for each of the at least one periods of time and each of the at least one road segments, the determining of the traffic density for the road segment of all the vehicles traveling on the road segment during the period of time is further based at least in part on the estimated average traffic speed of all the vehicles traveling on the road segment during the period of time.

4. The method of claim 3 wherein, for each of the at least one periods of time and each of the at least one road segments, the determining of the percentage traffic occupancy of at least one point on the road segment by all the vehicles traveling on the road segment during the period of time is further based at least in part on the estimated average traffic speed of all the vehicles traveling on the road segment during the period of time and on an estimated average length of all the vehicles traveling on the road segment during the period of time.

5. The method of claim 4 wherein, for each of the at least one periods of time and each of the at least one road segments, the determining of the traffic arrival rate volume at the road segment of all the vehicles traveling on the road segment during the period of time is further based at least in part on an estimated percentage of all the vehicles traveling on the road segment during the period of time that are the vehicles to which the data samples of the group correspond.

6. The method of claim 1 wherein, for each of at least one of the periods of time and each of at least one of the road segments, the determining of the traffic arrival rate volume of all the vehicles traveling on the road segment during the period of time includes generating a confidence value for the traffic arrival rate volume to reflect a degree of possible error in the traffic arrival rate volume, and wherein the using of the at least some determined traffic arrival rate volumes for the period of time includes using the generated confidence values to facilitate the future travel.

7. The method of claim 1 wherein the estimating of the traffic flow information of all the vehicles traveling on a road segment during a period of time is performed using recently received data samples in a realtime manner, and wherein the using of the at least some determined traffic arrival rate volumes, determined traffic densities, and determined percentage traffic occupancies for the period of time is further performed in a substantially realtime manner so as to facilitate imminent future travel on the one or more roads.

8. The method of claim 7 wherein the using of the at least some determined traffic arrival rate volumes, traffic densities, and percentage traffic occupancies for a period of time includes providing information about the determined traffic arrival rate volumes, traffic densities, and percentage traffic occupancies to one or more people considering upcoming travel on the one or more roads.

9. A computer-implemented method for determining estimated traffic flow information for vehicles traveling on roads based on data samples that reflect travel on those roads, the method comprising:

receiving indications of one or more segments of one or more roads, each road segment having multiple associated data samples that each are reported by one of multiple vehicles to reflect travel on the road segment by the one vehicle at a reported time;

for each of at least one of the road segments, automatically estimating traffic flow of vehicles traveling on the road segment during a period of time that includes the reported times of a group of the multiple data samples associated with the road segment, the automatic estimating being performed by one or more programmed computing systems during the period of time and including,

identifying the group of the multiple data samples associated with the road segment whose reported times occur during the period of time;

determining a quantity of vehicles that reported the data samples of the group, the vehicles that reported the data samples of the group being a subset of all vehicles that traveled on the road segment during the period of time; and

probabilistically assessing an estimated total quantity of all the vehicles that traveled on the road segment during the period of time based at least in part on the determined quantity of the vehicles that reported the data samples; and

using one or more of the estimated total quantities of vehicles to facilitate travel on the one or more roads.

10. The method of claim 9 wherein, for one or more of the at least one road segments, the probabilistic assessing of the estimated total quantity of all the vehicles that traveled on the road segment during the period of time includes determining a most probable total quantity of all the vehicles that traveled on the road segment during the period of time.

11. The method of claim 9 wherein, for one or more of the at least one road segments, the probabilistic assessing of the estimated total quantity of all the vehicles that traveled on the road segment during the period of time includes determining a confidence value for the estimated total quantity based at least in part on a likelihood of the estimated total quantity.

12. The method of claim 9 wherein, for one or more of the at least one road segments, the probabilistic assessing of the estimated total quantity of all the vehicles that traveled on the road segment during the period of time includes determining a traffic arrival rate volume of vehicles to at least one point of the road segment during the period of time, the determined traffic arrival rate volume being based at least in part on the estimated total quantity of all the vehicles that traveled on the road segment during the period of time.

13. The method of claim 12 wherein, for each of the one or more road segments, the determining of the traffic arrival rate volume of vehicles to at least one point of the road segment during the period of time includes using a probability distribution that represents probabilities for actual arrival rate volumes of vehicles given the determined quantity of vehicles that reported the data samples of the group for the road segment.

14. The method of claim 13 wherein, for each of the one or more road segments, the using of the probability distribution as part of the determining of the traffic arrival rate volume of the vehicles to at least one point of the road segment during the period of time includes determining a most probable traffic arrival rate volume.

15. The method of claim 13 wherein, for each of the one or more road segments, the using of the probability distribution as part of the determining of the traffic arrival rate volume of the vehicles to at least one point of the road segment during the period of time includes estimating confidence in the determined traffic arrival rate volume based on the probability distribution.

16. The method of claim 13 wherein, for each of the one or more road segments, the probability distribution is a Poisson distribution.

17. The method of claim 12 wherein, for each of the one or more road segments, the determining of the traffic arrival rate volume of vehicles to at least one point of the road segment during the period of time includes using a penetration factor for the road segment during the period of time, the penetration factor representing an estimated percentage of all the vehicles that traveled on the road segment during the period of time that are vehicles that reported the data samples of the group for the road segment.

18. The method of claim 12 wherein, for each of the one or more road segments, the at least one point of the road segment for which the traffic arrival rate volume of vehicles is determined is a beginning of the road segment.

19. The method of claim 12 wherein, for each of the one or more road segments, the at least one point of the road segment for which the traffic arrival rate volume of vehicles is determined is all of the road segment.

20. The method of claim 9 wherein, for one or more of the at least one road segments, the probabilistic assessing of the estimated total quantity of all the vehicles that traveled on the road segment during the period of time includes determining a traffic density for the road segment during the period of time, the determined traffic density being based at least in part on the estimated total quantity of all the vehicles that traveled on the road segment during the period of time.

21. The method of claim 20 wherein, for each of the one or more road segments, the determined traffic density represents a total quantity per unit of distance of all the vehicles that traveled on the road segment during the period of time.

22. The method of claim 20 wherein, for each of the one or more road segments, the determining of the traffic density for the road segment is based at least in part on at least one determined traffic arrival rate volume for the road segment during the period of time.

23. The method of claim 22 further comprising, for each of the one or more road segments, determining the at least one traffic arrival rate volumes for the road segment during the period of time so as to represent vehicles arriving to at least one point of the road segment during the period of time.

24. The method of claim 22 wherein, for each of the one or more road segments, the determining of the traffic density for the road segment is further based at least in part on an estimated average traffic speed of all the vehicles that traveled on the road segment during the period of time.

25. The method of claim 24 further comprising, for each of the one or more road segments, estimating the average traffic speed of all the vehicles that traveled on the road segment during the period of time.

26. The method of claim 20 wherein, for each of the one or more road segments, the determining of the traffic density for the road segment includes determining a most probable traffic density.

27. The method of claim 20 wherein, for each of the one or more road segments, the determining of the traffic density for the road segment includes estimating confidence in the determined traffic density.

28. The method of claim 9 wherein, for one or more of the at least one road segments, the probabilistic assessing of the estimated total quantity of all the vehicles that traveled on the road segment during the period of time includes determining a traffic occupancy for at least one point on the road segment during the period of time, the determined traffic occupancy being based at least in part on the estimated total quantity of all the vehicles that traveled on the road segment during the period of time.

29. The method of claim 28 wherein, for each of the one or more road segments, the determined traffic occupancy for the at least one point on the road segment represents an average percentage of time that the at least one point is occupied by at least one of the vehicles that traveled on the road segment during the period of time.

30. The method of claim 28 wherein, for each of the one or more road segments, the determining of the traffic occupancy for the road segment is based at least in part on at least one determined traffic density for the road segment during the period of time and on at least one estimated length of the vehicles that traveled on the road segment during the period of time.

31. The method of claim 30 wherein, for each of the one or more road segments, the determining of the traffic occupancy for the road segment is further based at least in part on at least one determined traffic arrival rate volume for the road segment during the period of time.

32. The method of claim 31 wherein, for each of the one or more road segments, the determining of the traffic occupancy for the road segment is further based at least in part on an estimated average traffic speed of all the vehicles that traveled on the road segment during the period of time.

33. The method of claim 32 further comprising, for each of the one or more road segments, determining the at least one traffic density for the road segment during the period of time, determining the at least one traffic arrival rate volume for the road segment during the period of time, and estimating the average traffic speed of all the vehicles that traveled on the road segment during the period of time.

34. The method of claim 28 wherein, for each of the one or more road segments, the determining of the traffic occupancy for the road segment includes determining a most probable traffic occupancy.

35. The method of claim 28 wherein, for each of the one or more road segments, the determining of the traffic occupancy for the road segment includes estimating confidence in the determined traffic occupancy.

36. The method of claim 9 wherein, for each of one or more of the at least some road segments, the estimating of the traffic flow of vehicles traveling on the road segment during a period of time is performed for each of multiple distinct periods of time.

37. The method of claim 9 wherein, for each of one or more of the at least some road segments, the estimating of the traffic flow of vehicles traveling on the road segment during a period of time is performed for each of multiple overlapping time windows during the period of time, such that at least some of the associated data samples for the road segment are used for each of multiple of the time windows.

38. The method of claim 37 wherein, for at least one of the one or more road segments, the multiple overlapping time windows during the period of time are modified to reflect one or more current conditions.

39. The method of claim 9 wherein, for each of one or more of the at least some road segments, the estimating of the total quantity of all the vehicles that traveled on the road segment during the period of time includes determining at least one confidence value for the estimated total quantity, and wherein the using of the one or more estimated total quantities of vehicles includes using one or more of the determined confidence values to facilitate future travel on the one or more roads.

40. The method of claim 9 wherein the using of the one or more estimated total quantities of vehicles includes providing indications of the one or more estimated total quantities of vehicles to one or more people to facilitate decisions by the people regarding travel on the one or more roads.

41. The method of claim 40 wherein the assessing of the one or more estimated total quantities and the using of the one or more estimated total quantities is performed in a substantially realtime manner relative to receiving the data samples used for the assessing, so as to enable substantially realtime decisions by the people.