Road congestion detection by distributed vehicle-to-vehicle communication systems

Abstract

The present invention relates to a method and apparatus for determining traffic condition comprising the steps of determining periodically a position data of a host vehicle 1, wherein the position data includes a time stamp, position, velocity and driving direction of the host vehicle 1, receiving periodically position data of at least an other vehicle 2, 3, 4, wherein the position data includes a time stamp, position, velocity and driving direction of the other vehicle 2, 3, 4, storing the position data of the host vehicle 1 and the position data of at least the other vehicle 2, 3, 4, calculating a relative position data, wherein the relative position data includes relative velocity and relative driving direction between the host vehicle 1 and the other vehicle 2, 3, 4, and judging a traffic condition based on the position data of the host vehicle 1, the position data of the other vehicle 2, 3, 4 and the relative position data.

Description

In the following, preferred embodiments and further details of the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 shows a scheme of the scenario of traffic condition detection.

FIG. 2 shows the table storing the position data of the other vehicles.

FIG. 3 shows an updated historical data table.

FIG. 4 shows a flowchart for updating the table.

FIG. 5 shows a flowchart of an in-vehicle calculation and request process at the host vehicle.

FIG. 6 shows a jam voting message set, and

FIG. 7 shows a flowchart of an in-vehicle calculation and reply process at another vehicle

FIG. 8 shows a flowchart of a jam voting process.

FIG. 9 shows a communication sequence diagram between the host vehicle and at least one other vehicle

FIG. 10 shows schematically an apparatus for road congestion detection.

FIG. 1 shows an overall scenario of traffic condition detection. The black nodes represent vehicles driving on a road 5, host vehicle 1 and other vehicles 2, 3, 4 are equipped with communication means and position detection means. Preferably, they are all inside the communication range of each other. The remaining vehicles 6 are either not equipped with communication means and position detection means or not within the communication range. Accordingly, these vehicles do neither participate to the communication network nor in the traffic condition detection process. The arrow 7 pointing away from each vehicle represents its velocity vector. The length of the arrow represents the travelling speed over ground of the vehicle, and the direction of the arrow represents the driving direction of the vehicle with regard to true north. The vectors are denoted as {right arrow over (V)}_i (i representing each vehicle). At a certain time t_i the position of vehicle i is denoted as P_i^t=[X_i,Y_i,Z_i], X_i representing the longitude, Y_i representing the latitude and Z_i representing the altitude of the vehicle.

The relative distance between any pair of vehicles i and j can be denoted as D_ij. D_ij can be calculated using the following formula

D _ij=√{square root over ((X_i−X_j)²+(Y_i−Y_j)²+(Z_i−Z_j)²)}{square root over ((X_i−X_j)²+(Y_i−Y_j)²+(Z_i−Z_j)²)}{square root over ((X_i−X_j)²+(Y_i−Y_j)²+(Z_i−Z_j)²)}  (1)

Accordingly, the distance between host vehicle 1 and the other vehicle 2 can be calculated as

D ₁₂=√{square root over ((X₁−X₂)²+(Y₁−Y₂)²+(Z₁−Z₂)²)}{square root over ((X₁−X₂)²+(Y₁−Y₂)²+(Z₁−Z₂)²)}{square root over ((X₁−X₂)²+(Y₁−Y₂)²+(Z₁−Z₂)²)}  (2)

The angle θ_ij between the driving directions of any pair of vehicles i and j can be calculated as

$\begin{array}{cc}\arccos \left({\theta }_{\mathrm{ij}}\right)=\frac{{\stackrel{->}{V}}_i\times {\stackrel{->}{V}}_j}{{\stackrel{->}{V}}_i*{\stackrel{->}{V}}_j},& \left(3\right)\end{array}$

wherein {right arrow over (V)}_i represents the velocity vector of vehicle i, {right arrow over (V)}_j represents the velocity vector of vehicle j, |{right arrow over (V)}_i| represents the amount of represents the amount of {right arrow over (V)}_j, and {right arrow over (V)}_i×{right arrow over (V)}_j represents the vector product between {right arrow over (V)}_i and {right arrow over (V)}_j

This angle θ_ij is calculated in order to identify the vehicles driving in opposite direction. Data received from vehicles driving in the opposite direction might not be considered for the traffic condition detection. If this angle θ_ij is lower than a predetermined threshold Th(θ_ij) (Th(θ_ij)≧θ_ij), it can be assumed that the pair of vehicles is driving generally in the same direction. In the case the angle θ_ij is larger than a predetermined threshold Th(θ_ij) (Th(θ_ij)<θ_ij), the vehicle is considered driving generally in the opposite direction. The position data from these vehicles driving in the opposite direction can be discarded from the traffic condition detection. For example, in FIG. 1, vehicle 4 is driving in the opposite direction of the host vehicle 1 and the other vehicles 2. Accordingly, any data sent from vehicle 4 might be discarded.

An angle δ denotes the angle between the velocity vector of vehicle i and the position vector from vehicle i to any other vehicle j in the communication network. The angle δ is calculated in order to identify if the vehicle j is located in an upstream direction or a downstream direction of vehicle i. The vector pointing from the vehicle i to the vehicle j is denoted as {right arrow over (ij)}. The amount of this vector {right arrow over (ij)} is equal to the relative distance between any pair of two vehicles D_ij.

{right arrow over (ij)}={right arrow over (j)}−{right arrow over (i)}=(Xj−Xi){right arrow over (X)}+(Yj−Yi){right arrow over (Y)}+(Zj−Zi){right arrow over (Z)}.  (4)

The angle δ between the vector {right arrow over (ij)} and the velocity vector {right arrow over (V)}_i of vehicle i is calculated

$\begin{array}{cc}\arccos \left({\delta }_{\mathrm{ij}}^t\right)=\frac{{\stackrel{->}{V}}_i\times \stackrel{->}{\mathrm{ij}}}{{\stackrel{->}{V}}_i*\stackrel{->}{\mathrm{ij}}},& \left(5\right)\end{array}$

wherein, {right arrow over (ij)} represents the position vector between vehicle i and vehicle j, {right arrow over (V)}_i represents the velocity vector of vehicle i, |{right arrow over (V)}_i| represents the amount of {right arrow over (V)}_i, |{right arrow over (ij)}| represents the amount of {right arrow over (ij)}, and {right arrow over (V)}_i×{right arrow over (ij)} represents the vector product between {right arrow over (V)}_i and {right arrow over (ij)}.

In the case the angle δ is less than a first predetermined threshold Th(δ₁) (Th(δ₁)≧δ), the vehicle j is considered at a downstream position traffic of the vehicle i. Contrary thereto, in the case the angle δ is larger than a second predetermined threshold Th(δ₂) (Th(δ₂)≦δ), the vehicle j is considered at an upstream position traffic of the vehicle i. Preferably, for detection of a vehicle at a downstream position, the first threshold Th(δ₁) can be set to equal or less than 90°, and for detection of a vehicle at an upstream position, the second threshold Th(δ₂) can be set to between 90° and 180°.

FIG. 2 shows an exemplary data table 20 for received position data from the other vehicles 2, 3, 4 within the communication range of the host vehicle 1. For each other vehicle, the data set includes a vehicle identifier (vehicle ID), a time stamp, a velocity vector (speed and driving direction) and the position. The vehicle data table is kept by the host vehicle 1. The vehicle ID is a temporary identifier of the other vehicle 2, 3 participating in the communication network assigned to the other vehicles 2, 3, 4 by a specific network configuration process of vehicle-to-vehicle communication system. The time stamp is the time when the data is sent out from the other vehicle 2, 3. In the case GPS is used, the time stamp can be changed every 1 sec. Time stamp is noted as t_i. The speed is the actual speed of the other vehicle 2, 3 over ground at time t_i, the unit is km/h. The direction is the actual driving direction of the vehicle with regard to true north. Speed and driving direction represent the velocity vector of the vehicle I, noted as {right arrow over (V)}_i. Position relates to the global geographic position measured by the position determining means, it is described with latitude X_i, longitude Y_i and altitude Z_i. The position can be expresses as a position vector P_i^t=[X_i,Y_i,Z_i].

Additionally, it is possible to have multiple data sets for one vehicle, wherein the data sets vary with respect to the timestamp.

FIG. 3 shows an extended data table 30, adapted for the use of traffic condition detection. The extended data table is based on the data table described with respect to FIG. 2. The same parameters such as vehicle ID, time stamp, speed, direction and position are denoted with the same identifiers. Additionally, the extended data table includes at least two further columns, time-to-expire, and relative distance. Time-to-expire represents the time limit when the data from the other vehicle 2, 3, 4 should be considered as too old and therefore should be discarded from the (extended) data table. The time-to-expire is measured in milliseconds and can be fixed or variable. The relative distance D_ij is the distance between any pair of host vehicle 1 and other vehicle 2, 3, 4. The relative distance D_ij is calculated according formula (1). Also in this table, the data of vehicles who are considered as in the opposite traffic direction of the host vehicle are also discarded.

FIG. 4 describes the flow chart for updating of the data tables 20, 30. When the host vehicle 1 receives a new position data from another vehicle 2, 3, 4, the update process is started. At step S41, the data is into the data table 20. Then at step S42, from the position data, the driving direction of the other vehicle 2, 3, 4 compared to the host vehicle 1 is calculated. At step S43 it is judged if the other vehicle 2, 3, 4 and the host vehicle 1, are travelling in the same direction. If the vehicles are travelling in the opposite directions (such as vehicle 4), the data set is discarded at Step S45. In the case the vehicles are travelling in the same direction, it is decided at step S44 if there is any data in the table 20 that has expired, as it is too old. If the data is too old, the data set is discarded at Step S45. In the case the vehicles are travelling in the same direction and the data has not been expired, the extended data table 30 is updated and modified for traffic condition detection.

FIG. 5 describes a flow chart for periodical in-vehicle process for calculation of a jam estimation value of the host vehicle 1. A timer is set up to define the periodical time interval. The calculation can begin from Start at step S50 when the timer is up. First, in step S51, the extended data table is checked according the process described with respect to FIG. 4. After that at step S52 the parameter v1 and at step S53 the parameter v2 is calculated.

v1 is the flag parameter for the traffic jam estimation based on the average speed E(V_i^t) during a time window tw of host vehicle 1 itself.

$\begin{array}{cc}E\left(V_i^t\right)=\frac{{\int }_{t-\mathrm{tw}}^tV_i^t}{t-\left(t-\mathrm{tw}\right)}=\frac{\sum _{t-\mathrm{tw}}^tV_i^t}{\mathrm{tw}}& \left(6\right)\end{array}$

If the vehicle is in the traffic jam, it is assumed that the vehicle drives at a lower speed A threshold Th(v1) is used to determine the value of v1. If the average speed E(V_i^t) is lower than Th(v1), the vehicle is considered as in the jam and v1 set to 1. If the average speed E(V_i^t) is larger than Th(v1), v1 is set to 0.

E(V_i^t)≦Th(v1)v1=1

E(V_i^t)>Th(v1)v1=0

v2 is the flag parameter for the relative traffic jam estimation value based on the relative speed ΔV_ij between each other vehicles 2, 3, 4 in the extended data table 30 and the host vehicle 1 itself.

ΔV _ij ^t =|E(V_i^t)−E(V_j^t)|  (7)

As many relative speeds can be calculated with the extended data table 30. Accordingly, it is assumed that vehicles farther away from the host vehicle 1 are less important to the traffic condition of the host vehicle 1. We take the inverse value of relative distance D_ij, namely 1/D_ij into account. As a result thereof, the larger the D_ij is, the less important it is for the relative speed between the host vehicle 1 and the respective other vehicles 2, 3, 4. An average relative speed of the host vehicle ΔV_i considering the relative distance can be calculated as:

$\begin{array}{cc}\Delta V_i^t=\frac{\sum _{j=1}^n\frac{\Delta V_{\mathrm{ij}}^t}{D_{\mathrm{ij}}^t}}{\sum _{j=1}^n\frac{1}{D_{\mathrm{ij}}^t}}& \left(8\right)\end{array}$

A threshold Th(v2) is used to determine the value of v2. If the relative speed ΔV_i^t is lower than Th(v2), the vehicle is considered as in the jam and v2 set to 1. If the relative speed ΔV_i^t is larger than Th(v2), v2 is set to 0.

ΔV _i ^t ≦Th(v2)v2=1

ΔV _i ^t >Th(v2)v2=0

After calculation of v1 and v2, different importance factors can be assigned to these two parameters at step S54 for integration of them. m is the importance for v1, n is the importance for v2. The average value of these two parameters is then.

$\begin{array}{cc}J=\frac{\left(v1*m+v2*n\right)}{\left(m+n\right)}& \left(9\right)\end{array}$

At step S55 it is judged if this parameter J is higher than a predetermined threshold Th(J), namely Th(J)≧J. In the case Th(J)≧J, the vehicle considers itself in the traffic condition and a voting flag J is set to 1 at step S56. In the case Th(J)≧J the process sets the flag J to 0 at step 57. If the flag J is set to 1, a jam voting message 60 is generated at the host vehicle 1 and at step S57 transmitted via the communication means to the others vehicles 2, 3, 4 within the communication range. After the value of J is determined, the timer is set up at step S59, the in-vehicle calculation process returns to the start point when this timer is up.

FIG. 6 describes the minimum message set of the jam voting message 60 generated by a vehicle 1, 2, 3, 4. The jam voting message 60 comprises at least one of request ID, vehicle ID, message type, time stamp, position, jam voting flag, time to expire value and a direction. A request ID is used to identify one round request-answer conversation between the host vehicle and any other vehicle. This request ID can be a unique number, or a time stamp when the request has been initiated, if it is so, request ID is equal to the time stamp of the request message. The message type defines if the jam voting message 60 is a request message (p=1) or a reply message (p=0). A reply message is transmitted at certain time T1 later after the other vehicle 2, 3, 4 has received a request message from the host vehicle 1. The time stamp is the time stamp in the reply message when the in-vehicle jam estimation process is carried out, the position represents position determined by the position determining means at the time stamp, the jam voting flag is the result of voting jam value J of the reply vehicle at the time stamp, it can be set to 1 (jam) or 0 (no jam), the time to expire indicates when the data set has expired and can be discarded from the data table 60, and the direction indicates the direction of the vehicle compared to true north at the time stamp.

A timer T1 is used to define the waiting time for sending out the reply message after having received the jam request message from the host vehicle 1. When the timer T1 is up, the system will find the latest periodical jam estimation result as determined in the FIG. 5. The reply message 60 can be generated based on the jam estimation result at this latest time stamp.

In the case the message type indicates a request message (p=1). The objectives of this message are at least to announce the traffic condition the host vehicle 1 to the other vehicles 2, 3, 4 within the communication range.

Every other vehicle 2, 3, 4 receiving a request message generates a reply message after waiting for a certain time T1, wherein the message type flag p is set to 0.

Accordingly, the jam voting flag J is the result of the calculation of other vehicles 2, 3, 4 within the communication range. If it is in jam, the flag J in the reply message is set to 1; if not, it will be set to 0.

The message type flag p is to distinguish if the message is a request message or a reply message from other vehicles. If it is a request message originated from a jammed vehicle, the message type is 1. If it is a reply message from the other vehicle 2, 3 which has received the request, the message type will be set to 0.

FIG. 7 shows the flow chart of the reply process at the other vehicle 2, 3, 4 once the vehicle has received a broadcasted request voting message from the host vehicle 1. The process starts at the step S60 after the other vehicle 2, 3, 4 has received a request voting message at step S65. The system will turn to sleep and wait the timer T1 is up at step S61. At step S62, the system checks the periodical jam estimation results J as described with reference to FIG. 5 in the memory. The time stamp which is closest to the time that the timer is up is be found out at this step S62. Next, at the step S63, the latest results of the jam estimation of this latest time stamp is used to generate the jam reply message 60, wherein the jam estimation results include at least the latest time stamp, J value at this time stamp, and the position data of the vehicle at this time stamp. At last step S64, the reply message is broadcasted to the vehicle-to-vehicle communication network.

FIG. 8 shows the flow chart of the voting process in the host vehicle 1 based on the received replies from the other vehicles 2, 3, 4. The process begins at step S71 when the host vehicle 1 sends out a request message to other vehicle 2, 3, 4 (S70). The system is then turn to sleep and wait a certain time T2 at the step S72 in order to collect the reply messages. Another timer T2 is set up by the system for this waiting period. T2 should be larger than the timer T1 in order to leave the other vehicles to transmit the reply message.

When the timer T2 is up, the system will begin to check the reply messages by one by at the step 73. For each reply message, it is judged, at the step 74, if the vehicle issuing the reply message does travel in the same driving direction as the host vehicle 1. If the other vehicle does travel in the same direction, the process is continued at step S75, otherwise, the reply message is discarded at step S82 and the process returns to the step S73 and starts to check the next reply message. At step S75 it is judged if the other vehicle is driving upstream of the host vehicle 1 by calculating the angle δ compared to the host vehicle 1. Accordingly, this calculation divides the vehicles into two groups: a group of upstream vehicles and a group of downstream vehicles. Voting message counters are set at the host vehicle 1 at steps S76 and S77 to count the number of reply messages. The number of the messages from upstream traffic is denoted as N_u, from the downstream traffic is denoted as N_d. Additionally, the counting can also separated by the value of the jam voting flag J. Accordingly, there may be at lest 2 counters needed.

└N_u^J=1,N_u^J=0,N_d^J=1,N_d^J=0┘

If the host vehicle counts more than 2 replies from upstream traffic at step S78 or downstream traffic at step S79, the counting process is continued at the step S80, otherwise, the process returns to the step S73 and continues to check other received reply messages during the timer T2. For each direction, we calculate the percentage of the messages with jam (J=1) at step S81. N_up denoted the percentage of jam (J=1) replies in an upstream direction, N_dp denotes the percentage of jam (J=1) replies in a downstream direction. Therefore, if N_u^J=1+N_u^J=0≧2 then

$N_{\mathrm{up}}=\frac{N_u^{J=1}}{\left(N_u^{J=1}+N_u^{J=0}\right)}$

and if N_d^J=1,N_d^J=0≧2 then

$N_{\mathrm{dp}}=\frac{N_d^{J=1}}{\left(N_d^{J=1}+N_d^{J=0}\right)}$

(see steps S78-S81)

If any of the two percentages is more than the threshold Th(Nth), the host vehicle 1 is in the traffic condition (step S83), otherwise, the process will return to the start until the next jam request message is broadcasted.

If the difference of the percentage N_up and the percentage N_dp is larger than a predetermined threshold value N_ph (step S84), the host vehicle 1 is at or near the head of the traffic condition (step S87). If the difference of the percentage N_up and the percentage N_dp is less than a predetermined threshold value N_pe (step S85), the host vehicle 1 is at or near the end of the traffic condition (step S86). These thresholds N_ph and N_pe can be calibrated prior the use or adapted during a learning phase.

• • If N_up≧Th(Nth) or N_dp≧Th(Nth), the host vehicle is in jam
  • if N_up−N_dp≧N_ph, the host vehicle is in the head of jam
  • If N_up−N_dp≦N_pe, the host vehicle is in the end of jam

After the position of the host vehicle 1 with respect to the traffic condition has been determined, said traffic jam information is transmitted as a traffic condition information message and/or a jam information message at step S88.

FIG. 9 shows a communication sequence diagram for the voting process for any pair of the vehicles. On the left is the time sequence of the host vehicle, on the right side is the time sequence of the other vehicle. In both vehicles, the periodical jam estimation process as described in the FIG. 5 is carried out separately. Consequently, multiple jam estimation results are obtained for different time stamp, wherein the jam estimation results include the time stamp, the jam estimation value J, and the position data of the vehicle at this time stamp. At time t1, the host vehicle detects a jam (J=1) and broadcast a jam voting request message into the vehicle-to-vehicle communication network. This jam request message is received by the other vehicle at time t2, the timer T1 is set up at t2. When the timer T1 is up at t3=t2+T1, the other vehicle will check the latest jam estimation time stamp, which is t4. The jam estimation result of the time stamp t4 will be set as a reply message 60 and sent back to the host vehicle. t5 is the time when the reply message is received by the host vehicle.

On the host vehicle side, when the request message is sent out at t1, it will at the same time set up a timer T2 (T2>T1) to wait for the replies from other vehicles in the network. The timer T2 is up at the moment t6, t6=t1+T2. From the time t6, the voting process will start as described in FIG. 8 at the step S73.

FIG. 10 shows schematically the apparatus for a road congestion detection. The apparatus may comprise a position determining means 10, a calculation means, a communication means and a memory means. The calculation means may further comprises one of traffic condition judging means 14, relative velocity calculation means 13, traffic jam estimation value means 16, weighting means 17 and traffic condition determining means 21. The communication means may further comprise a broadcasting means 18 and receiving means 26. The memory means may further comprise storing means 12, discarding means 15 and timer setup means 19. All means are connected by a bus. The above described apparatus can be realized in software, in hardware or in a combination thereof.

Features, components and specific details of the structures of the above-described embodiments may be exchanged or combined to form further embodiments optimized for the respective application. As far as those modifications are readily apparent for an expert skilled in the art they shall be disclosed implicitly by the above description without specifying explicitly every possible combination, for the sake of conciseness of the present description.

Claims

1. Method for determining traffic condition comprising the steps of: determining periodically a position data of a host vehicle (1), wherein the position data includes a time stamp, position, velocity and driving direction of the host vehicle (1),receiving periodically position data of at least an other vehicle (2, 3, 4), wherein the position data includes a time stamp, position, velocity and driving direction of the other vehicle (2, 3, 4),storing the position data of the host vehicle (1) and the position data of at least the other vehicle (2, 3, 4),calculating a relative position data, wherein the relative position data includes relative velocity and relative driving direction between the host vehicle (1) and the other vehicle (2, 3, 4), andjudging a traffic condition based on the position data of the host vehicle (1), the position data of the other vehicle (2, 3, 4) and the relative position data.

2. Method according to claim 1, wherein the position data of the other vehicle (2, 3, 4) is discarded when the angle of the relative direction between the host vehicle (1) and the other vehicle (2, 3, 4) is larger than a predetermined angle.

3. Method according to claim 1 or 2, wherein the position data of the other vehicle (2, 3, 4) is discarded when the time interval between the timestamp of the other vehicle (2, 3, 4) and the actual time is larger than a predetermined period.

4. Method according to at least one of claims 1 to 3, wherein based on the position data of the host vehicle (1) a traffic jam estimation value is determined and based on the relative position data between the host vehicle (1) and the other vehicle (2, 3, 4) a relative traffic jam estimation value is determined.

5. Method according to at least one of the preceding claims, wherein based on the relative position data, the traffic jam estimation value and the relative traffic jam estimation value are weighted.

6. Method according to at least one of the preceding claims, wherein based on the traffic jam estimation value and the relative traffic jam estimation value a voting jam value is determined.

7. Method according to claim 6, wherein based on the voting jam value a voting request message is broadcasted by the host vehicle (1).

8. Method according to at least one of the preceding claims, wherein the other vehicle (2, 3, 4) broadcasts a voting reply message as response to the voting request message of the host vehicle (1).

9. Method according to at least one of the preceding claims, wherein based on the voting request message and the voting reply messages received by the host vehicle (1) the traffic condition is determined.

10. Method according to at least one of the preceding claims, wherein based on the voting request message and the voting reply messages the position of the host vehicle (1) in respect to the traffic condition is determined.

11. Method according to at least one of the preceding claims, wherein based on the position of the host vehicle (1) in respect to the traffic condition a corresponding traffic condition message is broadcasted.

12. Apparatus for determining traffic condition comprising: a position determining (10) means for periodically determining a position data of a host vehicle (1), wherein the position data includes a time stamp, position, velocity and driving direction of the host vehicle (1),a receiving means (11) for periodically receiving position data of at least an other vehicle (2, 3, 4), wherein the position data includes a time stamp, position, velocity and driving direction of the other vehicle (2, 3, 4),a storing means (12) for storing the position data of the host vehicle (1) and the position data of at least the other vehicle (2, 3, 4),a relative position calculating means (13) calculating a relative position data, wherein the relative position data includes relative velocity and relative driving direction between the host vehicle (1) and the other vehicle (2, 3, 4), anda traffic condition judging (14) means for judging the traffic condition based on the position data of the host vehicle (1), the position data of the other vehicle (2, 3, 4) and the relative position data.

13. Apparatus according to claim 12, wherein a discarding means (15) discards the position data of the other vehicle (2, 3, 4) when the angle of the relative direction between the host vehicle (1) and the other vehicle (2, 3, 4) is larger than a predetermined angle.

14. Apparatus according to claim 12 or 13, wherein the discarding means discards the position data of the other vehicle (2, 3, 4) when time interval between the timestamp of the other vehicle (2, 3, 4) and the other vehicle (2, 3, 4) and the actual time is larger than a predetermined period.

15. Apparatus according to at least one of claims 12 to 14, wherein a traffic jam estimation value means (16) determines a traffic jam estimation value based on the position data of the host vehicle (1) and a relative traffic jam estimation value based on the relative position data between the host vehicle (1) and the other vehicle (2, 3, 4).

16. Apparatus according to at least one of claims 12 to 15, wherein a weighting means (17) determines a weighting factor based on the relative position data, the traffic jam estimation value and the relative traffic jam estimation value.

17. Apparatus according to at least one of claims 12 to 16, wherein a voting jam determining value means determines a voting jam value based on the traffic jam estimation value and the relative traffic jam estimation value.

18. Apparatus according to at least one of claims 12 to 17, wherein a broadcasting means (18) broadcasts a voting request message of the host vehicle (1) based on the voting jam value or a voting reply message of the other vehicle (2, 3, 4).

19. Apparatus according to at least one of claims 12 to 17, wherein the receiving means (11) receives a voting reply message from the other vehicle (2, 3, 4) or a voting request message from the host vehicle (1).

20. Apparatus according to at least one of claims 12 to 17, wherein a timer setup means (19) sets up a timer to generate the reply message at the other vehicle (2, 3, 4) side or to collect the reply messages at the host vehicle (1) side.

21. Apparatus according to at least one of claims 12 to 20, wherein a traffic condition determining means (21) determines a traffic condition based on the voting request message and at least one received voting reply message.

22. Apparatus according to at least one of claims 12 to 21, wherein the position determining means (10) determines the position of the host vehicle (1) in respect to the traffic condition based on the voting request message and the voting reply message.

23. Apparatus according to at least one of claims 12 to 22, wherein the broadcasting means (18) broadcasts a corresponding traffic condition message based on the position of the host vehicle (1) in respect to the traffic condition.