Traffic flow monitoring

• US 6,650,948 B1
• Filed: 11/28/2000
• Issued: 11/18/2003
• Est. Priority Date: 11/28/2000
• Status: Expired due to Term

• Current Assignee: TomTom Traffic B.V. (TomTom NV)
• Original Assignee: Applied Generics Ltd. (TomTom NV)
• Inventors: Atkinson, Ian Malcolm, Dixon, Michael Joseph, Adam, Thomas Bruce Watson
• Primary Examiner(s): Gordon, Paul P.
• Application Number:
  US09/722,660
• Time in Patent Office: 1,085 Days
• Field of Search: 700/66, 701/117, 701/118, 701/200, 701/207, 701/213, 340/995.1, 340/995.12, 340/995.13, 340/995.14, 340/995.19, 455/456.1, 455/456.6, 455/457
• US Class Current: 700/66
• CPC Class Codes: G08G 1/0104 Measuring and analyzing of parameters relative to traffic conditions
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination

Abstract

The present invention relates to a method for monitoring vehicular traffic flow in a road network 1 in an area served by a mobile telecommunications device network 7 having a call management system 10 provided with a mobile telecommunications device positioning system 11 providing positional data for active mobile telecommunications devices 12. The method comprises capturing geographical positioning data for individual active devices carried aboard vehicles 12 and converting these into probability vectors representing the likelihood of the vehicle having arrived at any of the possible road components 16 of the road network 7 compatible with the geographical positional data. As the vehicle 12 travels along, this process is repeated and new probability vectors constructed based on the probability of any of the available routes between the new probability vector road component position and the immediately preceding probability vector road component position. The expected transit time Δt_x for the available routes are computed and compared with actual transit times Δt to provide delay factors for the available routes and thereby the road components thereof. Average delay factors are obtained by making use of data obtained for other vehicles thereby to provide a report indicative of the degree of traffic congestion and delay on the roads. The invention also provides apparatus and computer software program products for use in implementing the invention.

Claims

1. A vehicular traffic flow monitoring method for monitoring vehicular traffic flow in a road network in an area served by a mobile telecommunications device network having a call management system provided with a mobile telecommunications device positioning system providing positional data in respect of at least active mobile telecommunications devices belonging to said mobile telecommunications device network, said method comprising the steps of:

a. capturing first geographical positional data for an active mobile telecommunications device in use on a vehicle at a given time t₁;

b. intersecting said first geographical positional data with road network mapping data defining said road network in terms of road components each representing a discrete part of the road network, so as to identify original possible road components corresponding to said first geographical positional data;

c. generating an initial probability vector representing the likelihood of said vehicle having arrived at a position on a given one of said original possible road for all of said original possible road components;

d. capturing second geographical positional data for said mobile telecommunications device at a later time t₂=t₁+Δ

t where Δ

t is the actual transit time of said device between said first and second geographical positions;

e. intersecting said second geographical positional data with said road network mapping data, so as to identify new possible road components corresponding to said second geographical positional data;

f. identifying available routes in the road network linking said possible road components corresponding to said first and second geographical positional data which routes are constituted by a series of road components;

g. generating an updated probability vector representing the likelihood of said vehicle having arrived at a position on a given one of said new possible road components in the road network corresponding to said second geographical positional data at said later time t₂ via one of said available routes, for all of said new possible road components;

h. intersecting said available routes with expected average vehicle speed data for the road components of each of said series of road components constituting said available routes so as to determine expected transit times for said available routes;

i. directly or indirectly comparing the actual transit time with the expected transit times for each of said available routes so as to produce delay factors for said routes indicative of the degree of vehicular traffic congestion on the individual road components thereof at the time; and

j. determining an average delay factor for a plurality of vehicles using a given road component, which average is weighted on the basis of at least the likelihood of any of the available routes having been followed.

2. A method as claimed in claim 1, which method also includes the steps of:

comparing expected route transit times with the actual transit time Δ

t, and revising the updated probability vector in the light thereof.

3. A method according to claim 1 wherein the geographical positional data is captured by using a positioning system selected from:

Cell Global Identify+Timing Advance, Uplink Time-of-Arrival, Enhance Observed Time Difference, and Assisted Global Positioning System.

4. A method according to claim 1 which includes the preliminary step of capturing proto-geographical positioning data comprising the identity of a transmitter receiver station and an individual timing advance zone thereof, and intersecting said proto-geographical positioning data with a GDF geographical mapping data file comprising mobile telecommunications network infrastructure mapping data, so as to provide geographical positional data defining the position of a timing advance zone in which said vehicle based mobile telecommunications device is present.

5. A method according to claim 1 in which the positioning system is used to capture proto-geographical positioning data and convert it into geographical positioning data defining the position of a timing advance zone in which said vehicle based mobile telecommunications device is present.

6. A method according to claim 1 in which the positioning system is used to generate geographical positioning data defining the coordinates of an area in which said vehicle-based mobile telecommunications device is present.

7. A method according to claim 1 which includes the preliminary step of redefining the road network mapping in a geographical mapping data file in terms of road components representing each direction of travel in respect of any roads for which different directions of travel are not represented separately.

8. A method according to claim 1 which includes the preliminary step of redefining the road network mapping in a geographical mapping data file in terms of road components having a length not greater than a predetermined maximum length.

9. A method according to claim 1 wherein said available routes linking possible road components indicated by said first and second geographical positional data are identified by using a route finding algorithm.

10. A method according to claim 1 wherein the updated probability vector including the likelihood of said vehicle having followed each of the available routes is determined by means of a transition matrix comprising:

possible road component positions and probabilities thereof defined by the initial probability vector, possible road component positions corresponding to said second geographical positional data, and said available routes linking said possible road component positions.

11. A method according to claim 10 wherein the likelihood of said vehicle having followed a given available route is weighted according to the relative compatibility of the actual transit time for said route with the expected transit time for said route whereby said transition matrix is converted to a time-dependent transition matrix.

12. A method according to claim 11 wherein routes having an expected transit time at least 20% greater than the actual transit time are disregarded.

13. A method according to claim 1 wherein individual vehicles included in the plurality of vehicles used for determining the average delay factor, are accorded a reduced weighting with increasing age of the actual transit time recorded for the individual vehicle concerned.

14. A method according to claim 13 wherein the weighting is progressively reduced to zero for increasing age up to an age of 10 minutes, whereby vehicle transit times determined more than 10 minutes previously are eliminated.

15. A method according to claim 1 wherein individual vehicles included in the plurality of vehicles used for determining the average delay factor are accorded a reduced weighting with increased transit time relative to those vehicles within said plurality having the shortest transit times.

16. A method according to claim 15 wherein data for individual vehicles having a transit time at least 50% greater than the median transit time for any of said plurality of vehicles, is disregarded.

17. A method according to claim 1 which includes the further step of exporting said delay factors to a user interface, for communication thereof to a user seeking a road traffic congestion report.

18. A method according to claim 17 which includes the step of converting said delay factor into a graphical and/or textual form indicative of the degree of road traffic congestion.

19. A method according to claim 1 wherein steps (d) to (j) are repeated cyclically in order to provide further updated probability vectors for a given vehicle and continue gathering route and transit time data for said vehicle for the purposes of determining average vehicle speeds for road components of downstream routes.

20. A road traffic network congestion reporting system suitable for use in conjunction with a mobile telecommunications device network having a call management system provided with a mobile telecommunications device positioning system, for monitoring and reporting on road traffic delays affecting the movement of vehicles through the road network, said reporting system comprising:

a storage device, and

a processor connected to said storage device,

the storage device storing;

i) road network data representing the geographical position of road components making up said road network;

ii) expected vehicle speed data for said road components of said road network; and

iii) a program for controlling the processor;

said processor operative with the program to;

a. capture first geographical positional data for an active mobile telecommunications device in use on a vehicle at a given time t₁;

b. intersect said first geographical positional data with road network mapping data defining said road network in terms of road components each representing a discrete part of the road network, so as to identify original possible road components corresponding to said first geographical positional data;

c. generate an initial probability vector representing the likelihood of said vehicle having arrived at a position on a given one of said original possible road for all of said original possible road components;

d. capture second geographical positional data for said mobile telecommunications device at a later time t₂=t₁+Δ

t where Δ

t is the actual transit time of said device between said first and second geographical positions;

e. intersect said second geographical positional data with said road network mapping data, so as to identify new possible road components corresponding to said second geographical positional data;

f. identify available routes in the road network linking said possible road components corresponding to said first and second geographical positional data which routes are constituted by a series of road components;

g. generate an updated probability vector representing the likelihood of said vehicle having arrived at a position on a given one of said new possible road components in the road network corresponding to said second geographical positional data at said later time t₂ via one of said available routes, for all of said new possible road components;

h. intersect said available routes with expected average vehicle speed data for the road components of each of said series of road components constituting said available routes so as to determine expected transit times for said available routes;

i. directly or indirectly compare the actual transit time with the expected transit times for each of said available routes so as to produce delay factors for said routes indicative of the degree of vehicular traffic congestion on the individual road components thereof at the time; and

j. determine an average delay factor for a plurality of vehicles using a given road component, which average is weighted on the basis of at least the likelihood of any of the available routes having been followed.

21. A reporting system as claimed in claim 20, wherein said processor is also operative to:

compare expected route transit times with the actual transit time Δ

t, and revise the updated probability vector in the light thereof.

22. A reporting system according to claim 20 wherein the geographical positional data is captured by using a positioning system selected from:

Cell Global Identify+Timing Advance, Uplink Time-of-Arrival, Enhance Observed Time Difference, and Assisted Global Positioning System.

23. A reporting system according to claim 20 wherein said processor is also operative initially to capture proto-geographical positioning data comprising the identity of a transmitter receiver station and an individual timing advance zone thereof, and intersect said proto-geographical positioning data with a geographical mapping data file comprising mobile telecommunications network infrastructure mapping data, so as to provide geographical positional data defining the position of a timing advance zone in which said vehicle based mobile telecommunications device is present.

24. A reporting system according to claim 20 in which the positioning system is used to capture proto-geographical positioning data and convert it into geographical positioning data defining the position of a timing advance zone in which said vehicle based mobile telecommunications device is present.

25. A reporting system according to claim 24 wherein data for individual vehicles having a transit time at least 50% greater than the median transit time for any of said plurality of vehicles, is disregarded.

26. A reporting system according to claim 20 in which said road network mapping data is in a geographical mapping data file in the form of road components representing each direction of travel for all bidirectional roads, including bidirectional single carriageway roads.

27. A reporting system according to claim 20 in which said road network mapping data is in a geographical mapping data file in the form of road components having a length not greater than a predetermined maximum length.

28. A reporting system according to claim 20 wherein said processor is operative to identify said available routes linking possible road components indicated by said first and second geographical positional data by use of a route finding algorithm.

29. A reporting system according to claim 20 wherein the processor is operative to update probability vectors including the likelihood of said vehicle having followed each of the available routes, by use of a transition matrix comprising:

possible road component positions and probabilities thereof defined by the initial probability vector, possible road component positions corresponding to said second geographical positional data, and said available routes linking said possible road component positions.

30. A reporting system according to claim 29 wherein the likelihood of said vehicle having followed a given available route is weighted according to the relative compatibility of the actual transit time for said route with the expected transit time for said route whereby said transition matrix is converted to a time-dependent transition matrix.

31. A reporting system according to claim 30 wherein routes having an expected transit time at least 20% greater than the actual transit time are disregarded.

32. A reporting system according to claim 20 wherein individual vehicles included in the plurality of vehicles used for determining the average delay factor, are accorded a reduced weighting with increasing age of the actual transit time recorded for the individual vehicle concerned.

33. A reporting system according to claim 32 wherein the weighting is progressively reduced to zero for increasing age up to an age of 10 minutes, whereby vehicle transit times determined more than 10 minutes previously are eliminated.

34. A reporting system according to claim 20 wherein individual vehicles included in the plurality of vehicles used for determining the average delay factor are accorded a reduced weighting with increased transit time relative to those vehicles within said plurality having the shortest transit times.

35. A reporting system according to claim 20 in which the positioning system is used to generate geographical positioning data defining the coordinates of an area in which said vehicle-based mobile telecommunications device is present.

36. A reporting system according to claim 20 which includes a user interface and the processor is further operative to export said delay factors to said user interface, for communication thereof to a user seeking a road traffic congestion report.

37. A reporting system according to claim 36 wherein said processor is further operative to convert said delay factor into a graphical and/or textual form indicative of the degree of road traffic congestion.

38. A reporting system according to claim 20 wherein said processor is operative to repeat cyclically processing steps (d) to (j) in order to provide further updated probability vectors for a given vehicle and continue gathering route and transit time data for said vehicle for the purposes of determining average vehicle speeds for road components of downstream routes.

39. A vehicular traffic monitoring system suitable for use in the method of the present invention and comprising a computer system having:

a storage device;

a processor connected to the storage device; and

at least one interface connected to the processor, the storage device storing digital mapping information for a road network, expected vehicle speed for road components of said road network, and a database of at least;

probability vectors representing the likely positions of moving active mobile telecommunications devices over a period of time and the likely routes thereof to said likely positions, and current road delay factor information;

said at least one interface coupling said processor to a mobile telecommunications device network call management system for interrogating said management system and receiving positioning data for active individual mobile telecommunications device therefrom; and

coupling said processor to user enquiry systems for receiving road traffic delay enquiries from, and transmitting road traffic delay reports to, said user enquiry systems; and

the processor operative with the program to;

a) capture geographical positional data for a mobile telecommunications device;

b) intersect said geographical positional data with road network mapping data defining said road network in terms of road components each representing a discrete part of the road network, so as to identify possible road components corresponding to said geographical positional data;

c) generate a probability vector representing the likelihood of said vehicle having arrived at a position on any of said possible road components;

d) identify available routes in the road network linking said possible road components corresponding to a given geographical positional data and preceding possible road component corresponding to a preceding geographical positional data, which routes are constituted by a series of road components;

e) intersect said available routes with expected average vehicle speed data for the road components of said series of road components constituting said available routes so as to determine expected transit times for said available routes;

f) directly or indirectly compare the actual transit time with the expected transit time for each of said available routes so as to produce delay factors for said routes indicative of the degree of vehicular traffic congestion on the individual road components thereof at the time;

g) determine an average delay factor for a plurality of vehicles using a given road component, which average is weighted on the basis of at least the likelihood of a given available route having been followed;

h) repeatedly update said database of moving active mobile telecommunication devices and road components with vehicle position and road delay factor information; and

i) retrieve road delay factor information from said database in response to enquiries from user enquiry systems and provide road delay factor reports thereto.

40. A computer program product comprising:

a computer usable medium having computer readable code means embedded in said medium, said computer readable code means comprising a report generator for monitoring vehicular traffic flow in a road network and providing reports on congestion on individual roads in said road network, said report generator comprising executable program code for execution by a computer coupled with a mobile telecommunications device network having a call management system provided with a mobile telecommunications device positioning system providing positional data in respect of at least active mobile telecommunications devices belonging to said mobile telecommunications device network, wherein said executable program code;

a) captures geographical positional data for a mobile telecommunications device;

b) intersects said geographical positional data with road network mapping data defining said road network in terms of road components each representing a discrete part of the road network, so as to identify possible road components corresponding to said geographical positional data;

c) generates a probability vector representing the likelihood of said vehicle having arrived at a position on any of said possible road components;

d) identifies available routes in the road network linking said possible road components corresponding to a given geographical positional data and a preceding possible road components corresponding to a preceding geographical positional data, which routes are constituted by a series of road components;

e) intersects said available routes with expected average vehicle speed data for the road components of said series of road components constituting said available routes so as to determine expected transit times for said available routes;

f) directly or indirectly compares the actual transit time with the expected transit time for each of said available routes so as to produce delay factors for said routes indicative of the degree of vehicular traffic congestion on the individual road components thereof at the time; and

g) determines an average delay factor for a plurality of vehicles using a given road component, which average is weighted on the basis of at least the likelihood of a given available route having been followed.