EP2267680A1

EP2267680A1 - Method and system for transmitting dynamic road traffic data to a user terminal

Info

Publication number: EP2267680A1
Application number: EP09305589A
Authority: EP
Inventors: Tomas Brezmes Llecha; Juan Luis Gorricho; Josep Cotrina Navau; Marc Rersa
Original assignee: France Telecom SA
Current assignee: Orange SA
Priority date: 2009-06-23
Filing date: 2009-06-23
Publication date: 2010-12-29
Anticipated expiration: 2029-06-23
Also published as: EP2267680B1

Abstract

The invention relates to a method for delivering road traffic data to at least a first position enabled user terminal of a plurality of position enabled user terminals, each of said position enabled user terminal being embarked on board a vehicle moving within a road infrastructure, said user terminal being connected through a telecommunication network to a road traffic management server.

According to the invention, the present method comprises the acts of:
■ receiving (400) at the road traffic management server positions and speed data from the plurality of position enabled user terminals,
■ estimating (401) road traffic data at a plurality of predefined checkpoints belonging to a mesh of redefined checkpoints matching the road infrastructure using the received positions and speed data;
■ producing (404) a road traffic estimated map by associating each redefined checkpoint with its estimated road traffic data;
■ transmitting (405) a portion of the road traffic estimated map to the first position enabled user terminal for subsequent display of said portion.

Description

FIELD OF THE PRESENT INVENTION:

The present invention generally relates to embedded applications aiming at providing road traffic information to drivers concerning the road traffic in its surroundings, both in real time and with sufficient accuracy to be relevant and useful for avoiding road traffic congestion.
Indeed, avoiding traffic congestion contributes to save time, gasoline, greenhouse gas emissions and stress.

BACKGROUND OF THE PRESENT INVENTION:

Today, road traffic data could be gathered using connected Personal Navigation Device (PND) through a mobile connection (GPRS or 3G), as well as a mobile with GPS embedded.
However, with existing solution, such road traffic data are not quite accurate regarding:

time span samples - there is no real-time information that could be seen by the drivers on their respective mobile terminal having GPS (for "Global positioning system") they embed in their respective car;
where user is located - in general, road info-traffic is available only in specific locations for major highways, roads or towns, but not in other specific locations or smaller roads.

Moreover, generally, to get road traffic data on its GPS mobile terminal or PND, a user must have previously subscribed under payment condition a subscription to a traffic information service.
In addition, road traffic data are generally produced by external entities aiming at supervising road traffic in predefined and specific road sections, using means such as camera video located by these specific road sections to evaluated instantaneous road traffic conditions before pushing information relative to these evaluated road traffic condition to traffic- information services.
In existing road traffic information services, no information is feedback from terminals of vehicle drivers.

SUMMARY OF THE PRESENT METHOD AND SYSTEM:

It is an objective of the present method and system to overcome disadvantages and/or make improvements other the prior art.
The following method/system will allow guaranteeing the user/ driver to get in real time and in a very simple and visual way, road traffic data concerning the road traffic that occurs in its surroundings area location.
The present method and system will also allow guaranteeing the user/ driver to get road traffic data, not only regarding specific locations for major highways, roads or towns, but for all specific locations or smaller roads.
The present method and system proposes an innovative way to obtain and display road traffic data for user/ driver using embedded GPS ('Global Positioning System') application running on personal navigation devices or mobile terminals (for instance a mobile phone) having a GPS function or device, so as to use information which is feedback from GPS terminals embedded in vehicle drivers.
To that extend, the present relates to a method for delivering road traffic data to at least a first position enabled user terminal of a plurality of position enabled user terminals, each of said position enabled user terminal being embarked on board a vehicle moving within a road infrastructure, said user terminal being connected through a telecommunication network to a road traffic management server.
According to the invention, the said method comprises the acts of:

■ receiving at the road traffic management server positions and speed data from the plurality of position enabled user terminals,
■ estimating road traffic data at a plurality of predefined checkpoints belonging to a mesh of predefined checkpoints matching the road infrastructure using the received positions and speed data;
■ producing a road traffic estimated map by associating each predefined checkpoint with its estimated road traffic data;
■ transmitting at least one portion of the road traffic estimated map to the first position enabled user terminal for subsequent display of said portion.

Thus, using at regular time intervals some geographical position and associated speed which are feedback from all mobile user terminals embedded in vehicle drivers and having GPS capabilities (for instance a GPS chip tracking the longitude and latitude coordinates and the instantaneous speed of the terminal from a satellites constellation), the road traffic information server will estimate road traffic conditions for a set of predefined checkpoints of a mesh of checkpoints defining short distance (from 200 meters to 1000 meters, for instance) road sections on a roadmap.
Previous to any traffic estimation calculation, such a mesh of checkpoints is initialized, built and completed, and finally stored in a memory of the road traffic management server, also based on localization data that are feedback from mobile user terminals embedded in vehicle drivers, as described in the following.
For each referenced checkpoint belonging to the mesh of checkpoint having longitude and latitude coordinates, road traffic condition in the surroundings of a particular checkpoint is estimated based on the position and speed sent to the road traffic management server by user terminals identified as located in the surroundings of the said particular checkpoint.
Then a traffic-map estimated map is produced by associating a road traffic estimation data to each checkpoint of the mesh of checkpoints, before being transmitted to each mobile user terminal for display in simple and visual way that will instantaneously and dynamically inform the vehicle driver about the road traffic-conditions around its geographical and instantaneous position on a dynamic digital roadmap view which is displayed on the terminal screen.
By this way, the method according to the invention provides several main advantages.
First, it provides a method that will guarantee the user/ driver to get in real time and in a very simple and visual way, dynamic road traffic information concerning the road traffic that occurs in its surroundings area location.
Second, it will also guarantee the user/ driver to get road traffic data, not only regarding specific locations for major highways, roads or towns, but for all specific locations or smaller roads, since road traffic data are directly feedback from terminals having localization means (for instance GSP device and/or function) and that have been embedded in the driver vehicle. Moreover, since the position and speed data are directly feedback from user terminal embedded in their respective vehicle, there is a high level accuracy of the source information that will benefit first the road traffic estimation calculation and, second, the quality of the road traffic estimations provided to drivers.
Third, using a predefined mesh of checkpoints defining road sections each having a short length from two hundred to a maximum of one thousand meters, as a basis of for estimating road traffic condition in the surroundings (for instance with a diameter 50 meters around a checkpoint) of each checkpoint of the mesh of checkpoints, provides to the method according to the invention a good level of accuracy regarding the delivered road traffic data displayed on user terminals, nearly in real time.
In a further embodiment of the method according to the invention, the said road traffic management server is further arranged to determine the portion of the road traffic estimated map by selecting checkpoints located within a given range of the latest position received from the first position enabled user terminal.
Thus is it is the road traffic management server, previously to the transmitting of the at least one portion of road traffic estimated map to the user terminal that selects the checkpoints to be displayed on the user terminal, thus limiting the volume of road traffic data to transmit to the first user terminal.
In an alternate embodiment of the invention, the said first position enabled user terminal is further arranged to determine the portion of the road traffic estimated map by selecting checkpoints in the said at least one portion of the road traffic estimated map transmitted by the said road traffic management server.
In this embodiment, it is an aim of the first enabled user terminal to adapt the received road traffic estimated map to display on the screen of the user terminal only the checkpoints of the mesh of checkpoints located in the surroundings of the first enabled user terminal.
By this way, a driver will also benefit an ergonomic overview display of road traffic conditions that occur on all roads located in the surroundings of its geographical position represented for instance in the centre of the screen view displayed on its mobile terminal. All the checkpoints of the mesh of checkpoints defining road sections located in the displayed surroundings of the driver geographical position (represented with a cross on figure 1) have been displayed above the digital roadmap presented on the terminal screen to the user, as a mask, with respective visual indications corresponding to road traffic conditions estimated at each checkpoint.
In another possible embodiment of the method according to the invention, the said act of estimating road traffic data at a particular checkpoint of the said mesh of checkpoints comprises the acts of :

■ grouping all the speed data corresponding to data positions that have been sent by the said enabled user terminals and which are located at a distance less than a predefined threshold distance from the said particular checkpoint ;
■ calculating using all the said speed data that have been grouped, at least one instantaneous road traffic data specific to the said particular checkpoint, for subsequent association to the said particular checkpoint.

In a specific embodiment of the invention, the said at least one instantaneous road traffic data is determined by calculating an average speed value using the said grouped speed data.
In a further embodiment of the invention, a road section being defined in between two checkpoints, the said method also comprises an act of calculating the said instantaneous road traffic data comprises complementary acts of:

■ identifying all the road sections of the said roadmap having the said particular checkpoint for extremity ;
■ calculating an estimated crossing time for each identified road sections, respectively, using the said calculated average speed value and by interpolating speed of the said grouped speed data.

In a further possible embodiment of the invention:

■ if the estimated crossing time calculated for a particular road section is less than a predefined minimum percentage of a referential average crossing time previously calculated for this particular road section, than the road traffic data will be classified as "discarded - to fast" on the said road section starting from the said particular checkpoint;
■ if the estimated crossing time calculated for a particular road section is greater than a predefined maximum percentage of a referential average crossing time previously calculated for this particular road section, than the road traffic data will be classified as "discarded - too slow" on the said road section starting from the said particular checkpoint;
■ if the estimated crossing time calculated for a particular road section is in between the said predefined minimum and maximum percentages of a referential average crossing time previously calculated for this particular road section, than the road traffic data will be classified as "acceptable" on the said road section starting from the said particular checkpoint.

In a possible embodiment of the invention, the said method comprises an act of coloring each checkpoints belonging to the at least one portion of the road traffic estimated map displayed on a screen of the first position enabler user terminal, with a predefined color depending on the average speed obtained from previous measures classified as "acceptable" and labeling this average value like "congested", "dense traffic" or "fluid" according to the "average speed" repository to the said road traffic data associated to the said each checkpoints, respectively.
In a further possible embodiment of the invention, the said method comprises a complementary act of transmitting to the first position enabler user terminal an alternative route for reaching a destination point previously requested by the user, when the said road traffic data associated to a particular checkpoint in the surroundings of which the first position enabler user terminal is located in, is classified as "congested".
In a specific embodiment of the invention, the method comprises a preliminary act for dynamically building the said mesh of checkpoints comprising the following steps of:

■ if there is no checkpoint closer than a minimum predefined distance around an instantaneous position enabled user terminal of a plurality of enabled user terminals, a new checkpoint is created to complete the said mesh of checkpoints with geographical coordinates corresponding to the said position of the said enabled user terminal;
■ matching the created checkpoint to the road infrastructure.

New creation of a checkpoint in the mesh of checkpoints could be done dynamically by the road traffic management server, but also manually by a user.
The invention also relates to a road traffic management server for delivering road traffic data to at least a first position enabled user terminal of a plurality of position enabled user terminals, each of said user terminal being embarked on board a vehicle moving within a road infrastructure, said user terminal being connected through a telecommunication network to said road traffic management server, said road traffic management server being operable to:

■ receive at the road traffic management server positions and speed data from the plurality of position enabled user terminals,
■ estimate road traffic data at a plurality of predefined checkpoints belonging to a mesh of predefined checkpoints matching the road infrastructure using the received positions and speed data;
■ produce a road traffic estimated map by associating each predefined checkpoint with its estimated road traffic data;
■ transmit a portion of the road traffic estimated map to the first position enabled user terminal for subsequent display of said portion.

In a further embodiment of the invention, the said server is arranged to determine the portion of the road traffic estimated map by selecting checkpoints located within a given range of the latest position received from the first position enabled user terminal.
The invention also relates to a position enabled user terminal for displaying road traffic data, said user terminal being connected through a telecommunication network to a road traffic management server and embarked on board a vehicle moving within a road infrastructure of a plurality of position enabled user terminals, said position enabled user terminal being operable to:

■ transmit to the road traffic management server positions and speed data from the position enabled user terminal,
■ receive a road traffic estimated map from the road traffic management server, said road traffic estimated map comprising a plurality of checkpoints mapping the road infrastructure, and associated with road traffic data estimating at least based on transmitted positions and speed data,
■ display a portion of the received traffic estimated map by displaying road traffic data related to checkpoints within a predefined neighborhood of current position of the position enabled user terminal.

The invention further relates to a system for delivering road traffic data to at least a first position enabled user terminal of a plurality of position enabled user terminals, each of said position enabled user terminal being embarked on board a vehicle moving within a road infrastructure, said user terminal being connected through a telecommunication network to a road traffic management server, said system comprising :

■ a road traffic management server (as the one described above) for delivering road traffic data to at least a first position enabled user terminal of a plurality of position enabled user terminals, each of said user terminal being embarked on board a vehicle moving within a road infrastructure, said user terminal being connected through a telecommunication network to said road traffic management server;
■ at least one position enabled user terminal (as the one described above) for displaying road traffic data, said user terminal being connected through a telecommunication network to the said road traffic management server and embarked on board a vehicle moving within a road infrastructure of a plurality of position enabled user terminals.

The invention also relates to a computer readable carrier including computer program instructions that cause a computer to implement a method according to the one described above, for delivering road traffic data to at least a first position enabled user terminal of a plurality of position enabled user terminals, each of said position enabled user terminal being embarked on board a vehicle moving within a road infrastructure, said user terminal being connected through a telecommunication network to a road traffic management server, said method comprising the acts of:

BRIEF DESCRIPTION OF THE DRAWINGS

The present system and method are explained in further detail, and by way of example, with reference to the accompanying drawings wherein:

FIG. 1 shows an embodiment of the system according to the invention;
FIG.2 shows the general flow data involving the client application running on the mobile user terminal having GPS capacities;
FIG.3 shows the data flows involved in the whole architecture of a system according to the invention, for delivering road traffic data on a plurality of mobile user terminals embedded in user vehicles;
FIG.4 is a block diagram illustrating the main steps of the method according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:

The following are descriptions of exemplary embodiments that when taken in conjunction with the drawings will demonstrate the above noted features and advantages, and introduce further ones.
In the following description, for purpose of explanation rather than limitation, specific details are set forth such as architecture, interfaces, techniques, etc., for illustration.
However, it will be apparent to that ordinary skill in the art that other embodiments that depart from these details would still be understood to be within the scope of the appended claims.
It should also be expressly understood that the drawings are included for illustrative purposes and do not represent the scope of the present system.
This invention proposes an innovative way to obtain and display dynamically traffic information for user with a GPS-embedded-mobile, under the assumption that user is using a mobile phone with GPS enabled capacities or devices.
In order to have relevant real-time information, the following steps are mandatory:

create and manage a mobile application, that will provide user position and speed as well as displaying relevant traffic information;
create and manage an application server, that will process mobile application inputs to send relevant traffic information to mobile application;
create and manage an application server web interface-module that will provide user a web interface.

The innovation resides mainly on:

how mobile application :
- ○ tracks the user location using the GPS chipset embedded on the mobile;
- ○ sends the positioning and speed information to the server at the specified pace;
- ○ displays traffic information map obtained in real-time from the server when requested due to origin and destination input;
how application server:
- ○ runs the algorithms to estimate traffic conditions;
- ○ composes the traffic information map in real-time on request;
- ○ stores traffic data for estimation based on history files.

So far, many modules have been developed in order to propose a prototype. There are three mains modules:

mobile application client:
- ○ manages the connection and interface with the application server.
- ○ tracks the user location using the GPS chipset embedded on the mobile.
- ○ sends the positioning and speed information to the server at the specified pace.
- ○ displays traffic information map obtained in real-time from the server when requested due to origin and destination input.
- ○ manages user favorite and recent destinations to simplify destination input;
application server core-module:
- ○ manages the connectivity with mobile clients
- ○ runs the algorithms to estimate traffic conditions
- ○ composes the traffic information map in real-time on request
- ○ stores user profiles (favorites, recent locations, route selection, etc.)
- ○ synchronizes information between mobile and web access
- ○ stores traffic data for estimation based on history files
application server web interface-module:
- ○ manages web interface access for the user
- ○ synchronizes information with the user profile
- ○ manages favorite destinations input
- ○ calculates routes
- ○ displays traffic information;

As illustrated on figure 1, when a car driver which is driving his car 100 activates its GPS enabled mobile terminal 101 through a connection 102 (for instance a GSM, GPRS or UMTS connection) to a telecommunication operator platform 103, the mobile GPS terminal sends F1 to a traffic management server 104 connected to the operator platform 103, at regular time intervals - for instance each 40 seconds, its instantaneous geographical position and speed the mobile GPS terminal 101 has received F2 from a constellation 106 of satellites.
Then, a traffic estimation program running on the traffic information server 104 will take into consideration of speed and positioning data it has received F1 in relation with a mesh of predetermined checkpoints (105₁, 105₂, 105₃, ..., 105_m) stored in a memory zone of the traffic information server 104 and that have been reported on the digital road map the user 100 sees on the screen 101' of its GPS mobile terminal (for instance a mobile phone with GPS capacities). Each of the checkpoints of the mesh of checkpoints are located on roads (without any size distinction). All pair of adjacent checkpoints belonging to the mesh of checkpoints define road sections being around one hundred meters long, so as to obtain close and representative traffic information delivered to be delivered in a colored and visual way to the driver 100 on the screen of its GPS mobile terminal 101.
At each end of the time period, the traffic estimation application running on the traffic information server 104 will identify for all checkpoints of the mesh of checkpoints, the users who are geographically located in its 50 meters surroundings using the received positioning data, respectively. For each of these drivers, it will considered and calculate with there respective speed previously transmitted to the server 104, an estimated average speed for crossing the road section the drivers are located on.
Then, if the estimated crossing time calculated for a particular road section is less than a predefined minimum percentage of a referential average crossing time previously calculated for this particular crossing time, than the traffic data will be classified as "discarded - too fast" on the said road section starting from the checkpoint around which drivers are located at a specific time interval.
If the estimated crossing time calculated for a particular road section is greater than a predefined maximum percentage of a referential average crossing time previously calculated for this particular crossing time, than the traffic data will be classified as "discarded - too slow" on the said road section starting from the checkpoint around which drivers are located at a specific time interval.
If the estimated crossing time calculated for a particular road section is in between the said predefined minimum and maximum percentages of a referential average crossing time previously calculated for this particular crossing time, than the traffic data will be classified as "acceptable" on the said road section starting from the checkpoint around which drivers are located at a specific time interval.
Then, the traffic estimation application running on the server 104 will execute an act of displaying at least one visual information representing instantaneous traffic data. Such an act consists in associating a specific color to each checkpoints of the said mesh of checkpoint starting a road section and that is located in the surroundings of the user terminal localization displayed on the screen, depending on the label given to the said traffic data associated with each of the said checkpoints (105₁, 105₂, 105₃, ..., 105_m), respectively.
For instance, a green colored checkpoint 105₁ will be representative of "fluid" road traffic on the road section close to the driver's position 107 driving on its route.
An orange colored checkpoint 105₃ displayed will be representative of a "dense traffic" road traffic on the road section 108 the driver's position 107 driving on its route is located on.
A red colored checkpoint 105₅ or 105₆ on figure 1, will be representative of a "congested" road traffic on the road section 108 the driver's position 107 driving on its route is located on, with potential traffic jam occurring close to this checkpoints 105₅ or 105₆.
Then, thanks to the invention, the driver is able to see real time traffic information over its digital roadmap displayed on the screen of its mobile GPS terminal (or other terminal with localization capacities) and, at the same time delivering at regular time intervals to a remote road traffic management server 104 and through an operator localization platform 103, its own geographical position and speed so as to benefit the traffic information service while keeping each driver's privacy.
The road traffic management server 104 sends back (arrow F3 on figure 1) for display on drivers' terminals and through the operator localization platform 103 and the telecommunication network 109 the requested road traffic data. These data are visually superimpose with a specific colored to the road map displayed on the screen of a driver's terminal, so as to deliver a quick and visual information to him relative to the current state of the traffic conditions around each checkpoints of the mesh of checkpoints.
As illustrated on figure 2, that presents data flow (arrows F20 and F21) involving the client application running on the mobile user terminal 201, there is a continuous user GPS tracking F20 between the GPS application or device embedded on the mobile phone 201 and at least one satellite 200. Based on this user GPS tracking, the user terminal 201 sends at regular time interval, for example from each ten to forty seconds, to a traffic management server 202 at least both information concerning the instantaneous positioning and speed of the user terminal 201 which is embedded in the car of the user.
As illustrated on figure 3, the traffic management server 302 receives F31 at each regular time interval a plurality of pairs of speed and positioning data from a plurality 300 of mobile terminals (300₁, 300₂, 300₃ , ... 300_n) respectively, registered by the real time traffic information service according to the present invention. Each mobile terminals (300₁, 300₂, 300₃ , ... 300_n) embeds a GPS device/ application aiming at tracking F30 data relative to its instantaneous geographical position and speed from requests to a constellation of satellites 301.
Using all the speed and positioning data received from the plurality 300 of user terminals (300₁, 300₂, 300₃, ... 300_n), the traffic information server 302 runs a specific algorithm to estimate the traffic conditions in the surroundings of each user terminal instantaneous position and relatively to checkpoints of a mesh of checkpoints which is stored in a memory zone of the traffic management server 302. For each terminal (300₁, 300₂, 300₃ , ... 300_n) of the plurality 300 of terminals, the traffic information server 302 will compose 303 dynamically the traffic information map with all the traffic data generated using an average of all the speed and positioning data relative to specific geographical respectively defined in a close surrounding of each checkpoint of the mesh of checkpoints.
Then, the traffic management server makes a push of each traffic information map for visualization on the screen of each corresponding user terminal (300₁, 300₂, 300₃, ... 300_n), respectively.
On the application Server-Core-Module, the road traffic estimation algorithm state process data as described below:

Any mobile sends a report (coordinates + time stamp) every 40 seconds;
For each report sent, the server looks for a milestone closer than α meter. If there is one, the report is saved, otherwise the report is discarded. This way only those reports useful to calculate the time spent in traveling from one milestone to another milestone will be saved.
If there is no milestone closer than β meters (β >> α) for a new report, a new milestone is created with the reported coordinates, saving also the present report. This way the milestones are created on line, and they are located keeping a distance of at least β meters among them.
Besides the new created milestone, if there is a previous report from the same user no older than γ seconds, not only the new milestone is created but also a new stretch is defined in between the new milestone and the previously visited one. To create a new stretch joining two milestones, both milestones must be visited sequentially by the same user, otherwise we do not know if there is a physical path between both milestones.
Take into account that as stated in the previous paragraphs, only those reports associated with milestones (closer than α meters) are saved, wherever the milestone is old or just created at the time.
For each saved report, the following algorithm runs:
- ○ the present and previous report from the same user are taken, if there is no previous report from that user the algorithm stops here.
- ○ from the last two reports from the same user we obtain the associated (closer) checkpoints, and from them we obtain the shortest path to go from one checkpoint to the other (sequence of stretches), if there is no path to link both checkpoints (no sequence of stretches found) the algorithm stops here. In practice, reporting every 40 sec. the path from one checkpoint to the other will be made up of 1, 2 or 3 stretches depending on the mobile velocity.
- ○ knowing the time interval between the two reports, this time interval is divided according to the stretch lengths among those which make up the path. For each stretch, a stretch-memory record is created with the time spent to traverse it. Now we need to label the stretch-memory record.
- ○ three stretch-memory labels are declared: "discarded - too slow", "discarded - too fast", "acceptable".
- ○ for each new stretch-memory created, the average crossing time on that stretch from previously recorded stretch-memories no older than 10 min. is calculated. If the present stretch-memory crossing time is less than 50% of the average crossing time, the label for the present stretch-memory will be "discarded - too fast"; if the crossing time is greater than 150% the average crossing time, it will be classified as "discarded - too slow"; if none of both cases happen, it will label the stretch-memory as "acceptable". This will be useful because, later on, only those stretch-memories classified as acceptable will be considered for the statistics.
- ○ if four consecutive stretch-memories are classified as "discarded - too fast" or "discarded - too slow", these stretch-memories switch their classification to acceptable, and the remaining stretch-memories from the last 10 min. are also switched accordingly.
- ○ simultaneously, with an offset on time, there is a parallel process which takes all the stretch-memories on periods of half an hour classified as acceptable calculating the average crossing time which is saved as the stretch average crossing time record. The complete list of measured average crossing time records for each stretch is classified in three different clusters applying the k-means clustering algorithm.
- ○ finally, to decide on line the road traffic state on each stretch, we obtain the present average crossing time on each stretch from the stretch-memories classified as "acceptable" in the last 10 min. and the resultant average value is classified according to the three clusters defined from the average crossing time records (former paragraph). Depending on the assigned cluster, the road traffic state will be estimated as fast (green colored), normal (orange colored) or slow (red colored).

This application can be used wherever road traffic data is needed but also from an ecological point of view allowing people to reduce greenhouse gas emissions.
Figure 4 describes the different steps of the method according to the invention.
Such a method is aiming at delivering road traffic data to at least a first position enabled user terminal of a plurality of position enabled user terminals, each of said position enabled user terminal being embarked on board a vehicle moving within a road infrastructure, said user terminal being connected through a telecommunication network to a road traffic management server, said method comprising the acts of:

■ receiving 400 at the road traffic management server positions and speed data from the plurality of position enabled user terminals,
■ estimating 401 road traffic data at a plurality of predefined checkpoints belonging to a mesh of predefined checkpoints matching the road infrastructure using the received positions and speed data;
■ producing 404 a road traffic estimated map by associating each predefined checkpoint with its estimated road traffic data;
■ transmitting 405 at least one portion of the road traffic estimated map to the first position enabled user terminal for subsequent display of said portion.

The said road traffic management server is further arranged to determine the portion of the road traffic estimated map by selecting checkpoints located within a given range of the latest position received from the first position enabled user terminal.
The said first position enabled user terminal could also be further arranged to determine the portion of the road traffic estimated map by selecting checkpoints in the said at least one portion of the road traffic estimated map transmitted by the said road traffic management server.
Moreover, the said act of estimating 401 road traffic data at a particular checkpoint of the said mesh of checkpoints comprises the acts of:

■ grouping 402 all the speed data corresponding to data positions that have been sent by the said enabled user terminals and which are located at a distance less than a predefined threshold distance from the said particular checkpoint ;
■ calculating 403 using all the said speed data that have been grouped, at least one instantaneous road traffic data specific to the said particular checkpoint, for subsequent association to the said particular checkpoint.

The said at least one instantaneous road traffic data is determined by calculating 401' an average speed value using the said grouped speed data.
In addition, a road section being defined in between two checkpoints, the said act of calculating 403 the said instantaneous road traffic data comprises complementary acts of:

■ identifying 403₁ all the road sections of the said roadmap having the said particular checkpoint for extremity ;
■ calculating 403₂ an estimated crossing time for each identified road sections, respectively, using the said calculated average speed value and by interpolating speed of the said grouped speed data.

Then:

■ if the estimated crossing time calculated for a particular road section is less than a predefined minimum percentage of a referential average crossing time previously calculated for this particular road section, than the road traffic data will be classified as "discarded - too slow" on the said road section starting from the said particular checkpoint;
■ if the estimated crossing time calculated for a particular road section is greater than a predefined maximum percentage of a referential average crossing time previously calculated for this particular road section, than the road traffic data will be classified as "discarded - too fast" on the said road section starting from the said particular checkpoint;
■ if the estimated crossing time calculated for a particular road section is in between the said predefined minimum and maximum percentages of a referential average crossing time previously calculated for this particular road section, than the road traffic data will be classified as "acceptable" on the said road section starting from the said particular checkpoint.

The method also comprises an act of coloring 406 each checkpoints belonging to the at least one portion of the road traffic estimated map displayed on a screen of the first position enabler user terminal, with a predefined color depending on the average speed obtained from previous measures classified as "acceptable" and labeling this average value like "congested", "dense traffic" or "fluid" according to the "average speed" repository to the said road traffic data associated to the said each checkpoints, respectively.
The method also comprises a complementary act of transmitting 407 to the first position enabler user terminal an alternative route for reaching a destination point previously requested by the user, when the said road traffic data associated to a particular checkpoint in the surroundings of which the first position enabler user terminal is located in, is classified as "congested".
The method also comprises a preliminary act for dynamically building 'INIT' the said mesh of checkpoints comprising the following steps of:

■ if there is no checkpoint in a minimum predefined distances around an instantaneous position enabled user terminal of a plurality of enabled user terminals, a new checkpoint is created to complete the said mesh of checkpoints with geographical coordinates corresponding to the said position of the said enabled user terminal;
■ matching the created checkpoint to the road infrastructure.

Claims

Method for delivering road traffic data to at least a first position enabled user terminal of a plurality of position enabled user terminals, each of said position enabled user terminal being embarked on board a vehicle moving within a road infrastructure, said user terminal being connected through a telecommunication network to a road traffic management server, said method comprising the acts of:
■ receiving (400) at the road traffic management server positions and speed data from the plurality of position enabled user terminals,

■estimating (401) road traffic data at a plurality of predefined checkpoints belonging to a mesh of predefined checkpoints matching the road infrastructure using the received positions and speed data;

■ producing (404) a road traffic estimated map by associating each predefined checkpoint with its estimated road traffic data;

■ transmitting (405) at least one portion of the road traffic estimated map to the first position enabled user terminal for subsequent display of said portion.
The method of claim 1, wherein the said road traffic management server is further arranged to determine the portion of the road traffic estimated map by selecting checkpoints located within a given range of the latest position received from the first position enabled user terminal.
The method of claim 1, wherein the said first position enabled user terminal is further arranged to determine the portion of the road traffic estimated map by selecting checkpoints in the said at least one portion of the road traffic estimated map transmitted by the said road traffic management server.
Method of claim 1, wherein the said act of estimating (401) road traffic data at a particular checkpoint of the said mesh of checkpoints comprises the acts of :
■ grouping (402) all the speed data corresponding to data positions that have been sent by the said enabled user terminals and which are located at a distance less than a predefined threshold distance from the said particular checkpoint ;

■ calculating (403) using all the said speed data that have been grouped, at least one instantaneous road traffic data specific to the said particular checkpoint, for subsequent association to the said particular checkpoint.
The method of claim 4, wherein the said at least one instantaneous road traffic data is determined by calculating (401') an average speed value using the said grouped speed data.
The method of claim 5, wherein a road section being defined in between two checkpoints, the said act of calculating (403) the said instantaneous road traffic data comprises complementary acts of:
■ identifying (403₁) all the road sections of the said roadmap having the said particular checkpoint for extremity ;

■ calculating (403₂) an estimated crossing time for each identified road sections, respectively, using the said calculated average speed value and by interpolating speed of the said grouped speed data.
The method of claim 6, wherein:
■ if the estimated crossing time calculated for a particular road section is less than a predefined minimum percentage of a referential average crossing time previously calculated for this particular road section, than the road traffic data will be classified as "discarded - too slow" on the said road section starting from the said particular checkpoint;

■ if the estimated crossing time calculated for a particular road section is greater than a predefined maximum percentage of a referential average crossing time previously calculated for this particular road section, than the road traffic data will be classified as "discarded - too fast" on the said road section starting from the said particular checkpoint;

■ if the estimated crossing time calculated for a particular road section is in between the said predefined minimum and maximum percentages of a referential average crossing time previously calculated for this particular road section, than the road traffic data will be classified as "acceptable" on the said road section starting from the said particular checkpoint.
The method of claim 7, wherein it comprises an act of coloring (406) each checkpoints belonging to the at least one portion of the road traffic estimated map displayed on a screen of the first position enabler user terminal, with a predefined color depending on the average speed obtained from previous measures classified as "acceptable" and labeling this average value like "congested", "dense traffic" or "fluid" according to the "average speed" repository to the said road traffic data associated to the said each checkpoints, respectively.
The method of claim 8, wherein it comprises a complementary act of transmitting (407) to the first position enabler user terminal an alternative route for reaching a destination point previously requested by the user, when the said road traffic data associated to a particular checkpoint in the surroundings of which the first position enabler user terminal is located in, is classified as "congested".
The method of claim 1, wherein it comprises a preliminary act for dynamically building (INIT) the said mesh of checkpoints comprising the following steps of:
■ if there is no checkpoint in a minimum predefined distances around an instantaneous position enabled user terminal of a plurality of enabled user terminals, a new checkpoint is created to complete the said mesh of checkpoints with geographical coordinates corresponding to the said position of the said enabled user terminal;

■ matching the created checkpoint to the road infrastructure.
A road traffic management server for delivering road traffic data to at least a first position enabled user terminal of a plurality of position enabled user terminals, each of said user terminal being embarked on board a vehicle moving within a road infrastructure, said user terminal being connected through a telecommunication network to said road traffic management server, said road traffic management server being operable to:
■ receive at the road traffic management server positions and speed data from the plurality of position enabled user terminals,

■ estimate road traffic data at a plurality of predefined checkpoints belonging to a mesh of predefined checkpoints matching the road infrastructure using the received positions and speed data;

■ produce a road traffic estimated map by associating each predefined checkpoint with its estimated road traffic data;

■ transmit a portion of the road traffic estimated map to the first position enabled user terminal for subsequent display of said portion.
The server of the previous claim 11, further arranged to determine the portion of the road traffic estimated map by selecting checkpoints located within a given range of the latest position received from the first position enabled user terminal.
A position enabled user terminal for displaying road traffic data, said user terminal being connected through a telecommunication network to a road traffic management server and embarked on board a vehicle moving within a road infrastructure of a plurality of position enabled user terminals, said position enabled user terminal being operable to:
■ transmit to the road traffic management server positions and speed data from the position enabled user terminal,

■ receive a road traffic estimated map from the road traffic management server, said road traffic estimated map comprising a plurality of checkpoints mapping the road infrastructure, and associated with road traffic data estimating at least based on transmitted positions and speed data,

■ display a portion of the received traffic estimated map by displaying road traffic data related to checkpoints within a predefined neighborhood of current position of the position enabled user terminal.
A system for delivering road traffic data to at least a first position enabled user terminal of a plurality of position enabled user terminals, each of said position enabled user terminal being embarked on board a vehicle moving within a road infrastructure, said user terminal being connected through a telecommunication network to a road traffic management server, said system comprising :
■ a road traffic management server according to claim 11 for delivering road traffic data to at least a first position enabled user terminal of a plurality of position enabled user terminals, each of said user terminal being embarked on board a vehicle moving within a road infrastructure, said user terminal being connected through a telecommunication network to said road traffic management server;

■ at least one position enabled user terminal according to claim 13 for displaying road traffic data, said user terminal being connected through a telecommunication network to the said road traffic management server and embarked on board a vehicle moving within a road infrastructure of a plurality of position enabled user terminals.
A computer readable carrier including computer program instructions that cause a computer to implement a method according to claims 1 to 10, for delivering road traffic data to at least a first position enabled user terminal of a plurality of position enabled user terminals, each of said position enabled user terminal being embarked on board a vehicle moving within a road infrastructure, said user terminal being connected through a telecommunication network to a road traffic management server, said method comprising the acts of:
■ receiving at the road traffic management server positions and speed data from the plurality of position enabled user terminals,

■ estimating road traffic data at a plurality of predefined checkpoints belonging to a mesh of predefined checkpoints matching the road infrastructure using the received positions and speed data;

■ producing a road traffic estimated map by associating each predefined checkpoint with its estimated road traffic data;

■ transmitting at least one portion of the road traffic estimated map to the first position enabled user terminal for subsequent display of said portion.