FR2879000A1 - Road information communicating method for e.g. super-highway vehicle on main road, involves programming management units of each vehicle and terminal during activation of dangerous running condition detecting sensors of terminals - Google Patents

Abstract

The method involves installing, along a roadway, terminals (B1, B2). Each vehicle is equipped with a short distance radio frequency communication transceiver (2) to receive signals from a short distance radio frequency communication transceiver (5) of terminals. Management units (1, 4) respectively of each vehicle and terminal are programmed during the activation of dangerous running condition detecting sensors (Cb1-Cbn) of terminals. An independent claim is also included for a system for exchanging and communicating road information.

Description

The invention relates to a method for communicating traffic information

  to motor vehicles traveling on a roadway. It extends to a system of exchange and communication of information implementing this method.

  At present, road information communication devices for motor vehicles are almost exclusively installed on motorways, and consist of: - information billboards permanently located, generally at railway stations; entry of motorway sectors, on which are displayed particular traffic information affecting a given motorway section: work between km (x) and km (y), fog at x km, rainy zone at x km ...

  - and provisional billboards intended for the signaling of temporary slowdown zones resulting from a fixed or mobile site, a stopper ...

  Consequently, outside of temporary slowdown zones, such as construction sites, ... reported specifically, no signage currently allows drivers to be informed of their imminent arrival in a temporary risk zone resulting, for example, from very severe weather conditions. located.

  The present invention aims to overcome this drawback and its main objective is to provide a method of communication of traffic information capable of systematically informing drivers of their imminent arrival in a risk zone, and to provide them with all useful information concerning the abnormal conditions. traffic that will be encountered.

  Another object of the invention is to provide a method of communication of traffic information making it possible to progressively inform the drivers of the approach of a risk zone.

  Another object of the invention is to provide a method of communicating traffic information, in addition to identifying risk areas, information on the measures to be taken to address these areas at risk under optimal conditions of road safety.

  Another object of the invention is to provide a method of communicating traffic information leading to a takeover of some vehicle control devices to allow to address risk areas in optimal road safety conditions.

  To this end, the invention relates to a method of communicating traffic information to motor vehicles traveling on a roadway, consisting of: É to install along the roadway a plurality of terminals arranged at a distance from each other and equipped with each: terrestrial telecommunication means comprising an identification address of said terminal, - short-distance radiofrequency communication means, - detection sensors for predetermined abnormal conditions of circulation, such as meteorological conditions, high traffic density, - and a data acquisition management unit derived from the means for detecting and controlling the terrestrial telecommunication means and the radio frequency communication means, É to equip each motor vehicle: - short-distance radiofrequency communication means, reception of the signals emitted by the radiof communication means frequency of the terminals, and a management unit of the signals received by the radiofrequency communication means, É and to program the respective management units of the terminals and vehicles so that, when activating a detection sensor of a given terminal, said original terminal: the management unit of this source terminal controls the transmission, by terrestrial telecommunication means, to n terminals, called relay terminals, arranged directly upstream of the said original terminal, with nz 1, of a signal comprising the identification of this source terminal and information on the abnormal conditions of circulation at the origin of the transmission of said signal, - the unit management of each of the n relay terminals controls the transmission, by the associated radiofrequency communication means, of a signal comprising information on the abnormal conditions of circulation at the origin of the transmission of said signal as well as on the distan separating this relay terminal from the original terminal, the management unit of each vehicle receiving a radiofrequency signal from a relay terminal controls the activation of visual and / or sound alarm information means of the driver of said vehicle.

  It should be noted that, throughout the text of this application, is meant to define by the term pavement, literally, the main and median part of a public road. According to this definition, a roadway can therefore be two-way traffic (mainly road such as national road, departmental ...) or single-handed traffic (mainly highway with two separate carriageways). 20 25

  In addition, terrestrial means of telecommunications is meant to define radio communication means of GSM (Global System Mobile), GPRS (Global Packet Radio System), UMTS, or the like.

  According to the invention, any abnormal traffic condition detected locally in an area covered by a detection sensor generates the transmission of information concerning the location of this area and the identification of risks, intended for all vehicles traveling upstream. of the said zone.

  Thus, all drivers are personally informed of the imminence of their arrival in an identified risk area and are therefore directly aware of the future traffic dangers they will encounter.

  In addition, according to the method of the invention, several relay terminals can be systematically activated, so that drivers are progressively informed of the proximity of risk areas, and are therefore inclined to gradually adapt their driving requirements security requirements.

  In addition, advantageously according to the invention, when activating a detection sensor of a given terminal, the management unit of each vehicle receiving a radio frequency signal from a relay terminal, and the means for visual and / or audible alarm of said vehicle, are adapted to deliver information concerning the identification of the area at risk (distance, abnormal traffic conditions), and instructions on the measures to be taken for security purposes road.

  In this way, drivers are not only informed of the imminence of their arrival in an identified risk area, but are also informed of the measures to be taken to safely approach the area.

  In addition, when activating a detection sensor of a given terminal, the management unit of each vehicle receiving a radiofrequency signal from a relay terminal, is programmed to perform a control takeover. control devices for vehicles, in order to comply with safety conditions when arriving in a risk area.

  According to this advantageous mode of implementation, a possible defect of vigilance of the drivers or a false maneuver of the latter, is compensated by the automatic takeover of control organs of the vehicles: limitation of the speed by action on the limiter of speed, ignition control of the dipped beam, tripping of the anti-collision system, hardening of the accelerator pedal ...

  Furthermore, advantageously according to the invention, when activating a detection sensor of a given terminal becoming the original terminal, the management unit of this original terminal controls the transmission by the terrestrial telecommunication means, to a centralized control station also provided with terrestrial telecommunication means, a signal including the identification of this original terminal and information on the abnormal traffic conditions at the origin of the emission of the said signal.

  This centralization at the level of a control station of the information from the various terminals located on a road and / or motorway sector provides a set of data facilitating notably the management of this sector.

  Moreover, in this case, and advantageously according to the invention, when receiving a signal emitted by an original terminal: E the centralized control station is adapted to control the transmission, to terminals arranged in upstream of the relay terminals, a signal comprising the identification of the original terminal and information on the abnormal conditions of circulation at the origin of the issuance of said signal, E the management unit of each of said terminals arranged upstream of the relay terminals is adapted to control the transmission, by the associated radiofrequency communication means, of a signal comprising information on the abnormal conditions of circulation at the origin of the transmission of said signal as well as on the distance separating this terminal from the original terminal.

  Thus, the vehicles are taken care of and the drivers are warned well upstream of the zones at risk, so as to provide a markup leading progressively to the respect of the conditions of safety required during the crossing of these zones at risks.

  Furthermore, the invention also aims at informing of the accidental presence of vehicles immobilized on a road surface, for example following a collision between vehicles, and for this purpose, according to the method of the invention, and advantageously: each vehicle is equipped on the one hand with terrestrial telecommunication means comprising an identification address of said vehicle, and on the other hand with sensors for detecting abnormal conditions of immobilization of this vehicle, management of the vehicles so as to command, when activating a detection sensor of an immobilization of one of said vehicles, a communication procedure adapted to deliver, to the terminal directly upstream of the vehicle, a signal containing information concerning the presence of said vehicle and the reasons for said presence, and programming the terminal management units so that, at a later date, tion of a signal representative of immobilization of a vehicle directly downstream of a terminal, the said terminal behaves like an original terminal.

  As examples of sensors for detecting abnormal immobilization conditions of a vehicle referred to above, mention may be made of shock sensors, airbag tripping sensors, abnormal cut-off sensors of the motor, triggering sensors for hazard warning lights ...

  In addition, in order to initiate a communication procedure, when activating a sensor for detecting immobilization of a vehicle, the respective management units of the vehicles and terminals are advantageously programmed in such a way that an identification of each terminal is made by the management unit of any vehicle passing in front of said terminal.

  By way of example, this identification can be obtained by controlling a continuous periodic transmission of the radiofrequency communication means of each terminal, so that each vehicle passing in front of a terminal receives a signal incorporating the identification address of said terminal.

  The invention extends to a traffic information exchange and communication system 15 implementing the communication method according to the invention. This system comprises: E a plurality of terminals equipped with: - terrestrial telecommunication means - short-distance radiofrequency communication means, - sensors for detecting predetermined abnormal conditions of circulation, such as meteorological conditions, - and a unit of data acquisition management from the means for detecting and controlling terrestrial telecommunication means and radiofrequency communication means, and a reception and information communication unit intended to be set up in each vehicle and comprising: radiofrequency communication means, and a signal management unit received by the radiofrequency communication means.

  In addition, this traffic information exchange and communication system advantageously comprises a centralized control station equipped with terrestrial telecommunication means to which, when activating a detection sensor of a given terminal becoming bounded of origin, the management unit of this source terminal controls the transmission of a signal comprising the identification of this source terminal and information on the abnormal traffic conditions at the origin of the transmission of said signal.

  According to the invention, the centralized control station of this traffic information exchange and communication system is, moreover, advantageously adapted, on reception of a signal transmitted by an origin terminal, to control the transmission , to terminals arranged upstream of the relay terminals, a signal comprising the identification of the original terminal and information on the abnormal conditions of circulation at the origin of the emission of said signal.

  In addition, according to an advantageous embodiment of this system for exchanging and communicating traffic information: E the unit for exchanging and communicating information of each vehicle, comprises terrestrial telecommunication means comprising an address of identification of said vehicle, and sensors for detecting abnormal conditions of immobilization of the vehicle, and the management unit of each of the units of exchange and communication of information equipping a vehicle is programmed, when the activation of a sensor for detecting immobilization of said vehicle, for controlling a communication procedure adapted to deliver, to the terminal directly upstream of this vehicle, a signal comprising information concerning the presence of said vehicle and the reasons of the said presence, É and the management unit of each terminal is programmed so that, on receipt of a signal representative of an imm obilisation of a vehicle directly downstream of a terminal, said terminal acts as an original terminal.

  Other features and advantages of the invention will become apparent from the detailed description which follows with reference to the accompanying drawings which represent by way of non-limiting example a preferred embodiment. In these drawings: FIG. 1 is a block diagram of a traffic information exchange and communication system according to the invention; FIG. 2 is a diagram representing a first operating scenario of this system; traffic information communication and exchange, - Figure 3 is a diagram representing a second operating scenario of this system of exchange and communication of traffic information, - and Figure 4 is a diagram showing a third operating scenario of this system of exchange and communication of traffic information.

  The traffic information exchange and communication system according to the invention represented by way of example in FIG. 1, is more particularly intended to be installed on a motorway infrastructure, and its main purpose is to inform in a preventive manner. drivers traveling on the said highway infrastructure, predetermined dangerous traffic conditions, such as weather conditions, traffic accident, presence of a stationary vehicle, high traffic density ...

  This information system is subdivided mainly into three types of complementary subsets consisting of (FIG. 2): E of the exchange and communication units GV intended to be loaded on the vehicles V1, V2, ... , Vn, É terminals B1-Bn intended to be arranged at a distance from each other along each of the pavement of the highway, - and a centralized PC control station.

  Firstly, each on-vehicle exchange and information communication unit GV on a vehicle V1, V2,..., Vn, comprises (FIG. 1): Cv1 sensors, ..., Cvn for the detection of conditions abnormal immobilization of the vehicle such as for example shock sensor, trigger sensor of an airbag, abnormal motor cut-off sensor, triggering sensor of the hazard warning lights ...

  E a short-distance radiofrequency communication transmitter / receiver 2, E terrestrial telecommunications means 3 comprising a vehicle identification address, É and a management unit 1 connected to the sensors Cv1-Cvn, to the transmitter / receiver 2, and terrestrial telecommunication means 3.

  Each terminal B1-Bn comprises: Cb1 sensors, ..., Cbn detection of hazardous traffic conditions such as: weather conditions (temperature, humidity, opacity, brightness sensors ... ), - a high traffic density, E a short distance radiofrequency communication transmitter / receiver 5, with a range adapted to cover, only, the width of the roadway along which terminal B1-Bn, E terrestrial means is located telecommunications terminal 6 having an identification address of the terminal, E and a management unit 4 connected to the sensors Cbl-Cbn, the transmitter / receiver 5, and the terrestrial telecommunication means 6.

  Finally, the centralized PC control station comprises terrestrial telecommunication means 7 including an identification address of said control station, for transmitting and receiving information to and from the terrestrial telecommunication means 3 , 6 respective units GV on vehicles V1, V2, ..., Vn, and B1-Bn terminals.

  According to the invention, furthermore, when activating a sensor Cv1-Cvn on a vehicle V1-Vn and / or a sensor Cb1-Cbn installed on a terminal B1-Bn, the respective management units 1, 4 of the GV exchange and communication units and said terminals B1-Bn, as well as the PC control station, are programmed to trigger specific event chains to inform drivers of the proximity of an area dangerous traffic.

  Thus, in the first place, and as illustrated by way of example in FIG. 2, when a sensor (s) Cbn of a terminal Bn is (are) activated (in FIG. example sensor (s) of terminal B1 signaling a rainy zone possibly of reduced visibility), the concerned terminal B1 is configured as the original terminal, and the following commands are triggered: the management unit of the original terminal B1 controls the transmission by terrestrial telecommunication means 6 of the latter, to the PC control station and n terminals B2, B3, said relay terminals, arranged directly upstream of said original terminal, (with n = 2 in the example of FIG. 2), a signal comprising the identification of this source terminal B1 and information on the abnormal conditions of circulation at the origin of the transmission of said signal, - the station centralized control PC controls the transmission to terminals Bn arranged upstream of the relay terminals B2, B3, a signal comprising the identification of the original terminal B1 and information on the abnormal conditions of circulation at the origin of the emission of said signal, - the management unit 4 of each of the relay terminals B2, B3 and each terminal Bn receiving the signal from the PC control station, controls the transmission by the respective radiofrequency transmitters / receivers 5 of said terminals, a signal for vehicles V1-V4 passing in front of the latter, comprising information on the abnormal conditions of circulation at the origin of the emission of said signal as well as on the distance separating these terminals B2, B3, Bn from the original terminal B1, the management unit 1 of each vehicle VI , V2 receiving a radiofrequency signal from a relay terminal B2, B3 or a terminal Bn located upstream of said relay terminals, controls the activation of visual and / or audible warning means of information of the driver of the said vehicle.

  All the drivers therefore receive a succession of messages of the type, for example, rainy zone at x meters or kilometers, informing them of their arrival in an identified risk zone, and providing them with a count of the residual distance separating them from this zone.

  The messages thus transmitted to the drivers may be audible and / or visual messages, and may comprise, in addition to the above-mentioned information identifying the zone at risk, instructions on the measures to be taken for road safety purposes, such as set-point for progressive reduction of vehicle speed, ignition control of dipped-beam headlamps ...

  It should be noted, in addition, that these instructions can also be accompanied by a takeover of certain control devices of the vehicles: speed limitation by action on the speed limiter, control of the ignition of the lights of crossing, tripping of the anti-collision system, hardening of the accelerator pedal ...

  It should also be noted that, according to the invention, the original terminal function can be assigned to a mobile terminal, that is to say to an indefinitely fixed terminal intended to signal, in a manner known per se. a temporary slowdown zone resulting from a fixed or mobile site, a plug.

  Moreover, as mentioned above the transmitter / receiver 5 equipping each terminal Bn has a range adapted to cover only the width of the roadway along which is located the said terminal.

  However, in order to avoid interference between the terminals arranged along a roadway and the vehicles traveling on the other roadway, resulting for example from a disturbance of the range of the transceivers 5 of the terminals, the system of information according to the invention comprises a terminal Bi (Figure 3), said initialization terminal disposed at each motorway entrance and each access ramp and adapted to transmit to each vehicle passing in front of said terminal a character identification of the direction of movement of this vehicle.

  In addition, the signal transmitted by each terminal Bn to the vehicles comprises, in the first place, the aforementioned identification character, so that by comparison between this identification character and the stored one initially received from the initialization terminal, the management unit 1 of each vehicle is able to select the only signals that are actually intended for it.

  The second scenario intended to be taken into account by the traffic information exchange and communication system according to the invention concerns the accidental presence of vehicles immobilized on a motorway pavement, for example and as represented in FIG. 3, following a collision between two vehicles VI, V2. The following process is then triggered by the information exchange and communication system according to the invention: the management units 1 of the immobilized vehicles VI, V2, in the example accidented, control the transmission by means of the terrestrial telecommunication means 3 on board, a signal to the terminal BI located directly upstream of said vehicles, including the position of the latter as well as information concerning the reasons for their immobilization, - the terminal B1 is configured as that origin terminal and controls the transmission by its terrestrial telecommunication means 6, to the PC control station and the two relay terminals B2, B3 arranged directly upstream of said original terminal, a signal comprising the identification of this original terminal B1 and information on the presence of the two vehicles V1, V2, the control station PC controls the transmission to terminals Bn disposed in upstream of the relay terminals B2, B3, a signal comprising the identification of the original terminal B1 and information on the presence of the two vehicles V1, V2, - the management unit 4 of each of the relay terminals B2, B3 and each terminal Bn receiving the signal from the PC control station, controls the transmission by the respective radiofrequency transmitters / receivers 5 of said terminals, a signal for V4-V7 vehicles passing in front of the latter, including information on the presence of the two vehicles VI, V2 as well as on the distance separating these terminals B2, B3, Bn from the original terminal BI, - the management unit 1 of each vehicle V4-V7 receiving a radiofrequency signal coming from a relay terminal B2, B3 or a terminal Bn located upstream of said relay terminals, controls the activation of visual and / or audible alarm means of information of the driver of said vehicle.

  According to this scenario, the drivers thus receive a succession of messages of the type, for example an accident zone at x meters or kilometers, informing them of their arrival in an identified risk zone, and providing them with a count of the residual distance separating them from this zone.

  As for the first scenario, these messages may be audible and / or visual messages, and may include, in addition to the above information identifying the area at risk, instructions on the measures to be taken for road safety purposes. , such as gradual reduction of vehicle speed, ignition control of hazard warning lights ...

  Finally, and as for the first scenario, these instructions can also be accompanied by a takeover of some control devices of the vehicles.

  It should be noted, moreover, that, according to this second scenario, when the distance between the immobilized vehicles V1, V2 and the original terminal B1 is greater than a given threshold distance, for example between one hundred meters and a few hundreds of meters, the management unit 1 of this original terminal B1 is programmed so that the said original terminal also becomes transmitting a radiofrequency signal information of the presence of immobilized vehicles at a given distance this original B1 terminal.

  The third scenario intended to be taken into account by the information exchange and communication system according to the invention concerns, as illustrated in FIG. 4, the contra-flow traffic of a vehicle VI on an exit ramp. of a pavement of a highway. According to the invention, and in the first place, the detection of such a vehicle VI takes place, for example, by arranging along the exit ramp two reference markers Br1, Br2: - remotely implanted one of the along the said ramp so as to be passed successively in a given order, for example Br1 then Br2, by a vehicle normally traveling on the ramp, - designed to deliver an alert signal when a vehicle VI exceeds said terminals in an inverse order of the pre-established order.

  This warning signal is, moreover, delivered to a terminal B1 similar to the installed terminals, according to the invention, along the roadways of the motorway, and thus mainly comprising a radio-frequency transmitter / receiver short distance 5, terrestrial means of telecommunication 6, and a management unit 4.

  During the transmission of such an alert signal by the reference marks Br1, Br2, the following process is triggered by the information system according to the invention: terminal B1 is configured as the original terminal, and its management unit 4 controls: É the transmission by the transmitter / receiver 5 of the said terminal of an alert message to the vehicle V1 flowing against the shoulder strap, É emission by terrestrial means 6 of this terminal B1, an alert signal to the PC control station and n relay terminals Bn, Bn + 1 disposed on the highway pavement directly upstream of the exit ramp, (with n = 2 in the example of FIG. 4), the control station PC controls the transmission of an alert signal to terminals Bn-1 arranged upstream of the relay terminals Bn, Bn + 1, the management unit 4 of each of the relay terminals Bn, Bn + 1 and of each terminal Bn-1 receiving the signal from the control station PC, controls the transmission by the respective radiofrequency transmitters / receivers 5 of said terminals, a signal intended for vehicles V2-V4, comprising information on the risks of presence of a vehicle VI traveling in opposite directions, the unit of management 1 of the vehicle V1 traveling in the opposite direction on the ramp controls the activation of visual and / or audible warning means of the driver of said vehicle, - the management unit 1 of each vehicle V2-V4 receiving a signal radio frequency coming from a relay terminal Bn, Bn + 1 or a terminal Bn-1 located upstream of said relay terminals, controls the activation of visual and / or audible warning means of the driver of the said vehicle.

  According to this process, the driver of the V1 vehicle traveling in the opposite direction receives an audible and / or visual message telling him to stop the vehicle on the right side of the ramp, such as for example if you are driving in the opposite direction, stop immediately. vehicle on the right side of the roadway. This message may also include instructions on other measures to be taken for road safety purposes, such as hazard warning lights ...

  In addition, and as for the first two scenarios, these instructions can also be accompanied by a takeover of some vehicle control organs such as. : speed limitation until complete stop by action on the speed limiter, control of the ignition of the hazard warning lights, tripping of the anti-collision system, hardening of the accelerator pedal ...

  The drivers of vehicles V2-V4 traveling on the highway upstream of the exit ramp, receive meanwhile a succession of audible and / or visual messages of the type for example vehicle traveling against detected direction x meters or kilometers. These messages may also include instructions on the measures to be taken for road safety purposes, such as the progressive reduction of the speed of the vehicle to stop said vehicle on the emergency stop band, command of ignition of hazard warning lights ...

  Finally, these instructions can also be accompanied by a takeover of some control devices of the vehicles.

  As mentioned above, the traffic information exchange and communication system according to the invention is more particularly intended to be installed on a motorway infrastructure. However, such a system can also be installed on a road infrastructure such as national road or even departmental road.

  In this case, in addition, the terminals can be arranged on either side of the roadway. However, in this case, the terminals and / or the vehicles must be equipped with means for recognizing the direction of movement of the vehicles such as satellite positioning means (GPS), means on board vehicles measuring the magnetic field level emitted by the transmitters / receivers 5 of the terminals Bn.

  The terminals may also be arranged along one side of the roads by means of an identification of the position, upstream or downstream of the receiving vehicle, of the origin terminal, which identification may notably be carried out using satellite positioning means ( GPS).

  It will be noted, in a variant, that the centralized control station (PC) previously described could also be adapted to control the terminals BI to B3 and not only the terminals located upstream of the relay terminals. This position could thus, mitigate any communication failure between terminals.

  Of course, the present invention is not limited to the embodiments described above and encompasses any variant within the scope of those skilled in the art. Thus, the terminals themselves could be provided with signaling means (sound or visual) to inform the driver of the imminence of his arrival in a risk area.

Claims (6)

  1 / A method of communicating traffic information to motor vehicles (V1-Vn) traveling on a roadway, characterized in that it consists: É to install along the roadway a plurality of terminals (B1-Bn) 5 arranged at a distance from one another and each equipped with: - terrestrial telecommunication means (6) comprising an identification address of said terminal, - short-distance radiofrequency communication means (5), - sensors (Cbl-Cbn ) for detecting predetermined abnormal conditions of circulation, such as meteorological conditions, high traffic density, and a management unit (4) for acquiring data from the detection sensors (Cbl-Cbn), and control terrestrial telecommunication means (6) and radiofrequency communication means (5), É to equip each motor vehicle (V1-Vn): - short-distance radiofrequency communication means (2), for receiving the signals transmitted by the radiofrequency communication means (5) from the terminals (B1-Bn), - and a management unit (1) of the signals received by the radio frequency communication means (2), É and to be programmed the respective management units (4, 1) of the terminals (B1-Bn) and the vehicles (V1-Vn) so that, when activating a detection sensor (Cbl-Cbn) of a given terminal (B1), said original terminal: - the management unit of this original terminal (B1) controls the transmission, by terrestrial telecommunication means (6), to n terminals (B2, B3) , said relay terminals, arranged directly upstream of said original terminal, with nz 1, of a signal comprising the identification of this original terminal (BI) and information on the abnormal conditions of circulation to the origin of the emission of said signal, - the management unit (4) of each of the n relay terminals (B2, B3) controls the transmission, by radiofr communication means associated quence (5), of a signal comprising information on the abnormal conditions of circulation at the origin of the transmission of said signal as well as on the distance separating this relay terminal (B2, B3) from the original terminal. (BI), the management unit (1) of each vehicle (V1-Vn) receiving a radiofrequency signal from a relay terminal (B2, B3) controls the activation of visual alarm means and / or informative sound of the driver of said vehicle.   2 / A method of communication according to claim 1 characterized in that, during the activation of a detection sensor (Cbl-Cbn) of a given terminal (B1), the management unit (1) of each vehicle (V1-Vn) receiving a radiofrequency signal from a relay terminal (B2, B3), and the visual and / or audible alarm means of said vehicle, are adapted to deliver information concerning the identification of the zone at risk (distance, abnormal traffic conditions), and instructions on the measures to be taken for road safety purposes.   3 / A method of communication according to one of claims 1 or 2 characterized in that, upon activation of a detection sensor (Cbl-Cbn) of a given terminal (BI), the management unit ( 1) of each vehicle (VI-Vn) receiving a radiofrequency signal from a relay terminal (B2, B3), is programmed to make a takeover control of the vehicle control organs, in order to comply with conditions of safety when arriving in a risk zone.   4 / A method of communication according to one of claims 1 to 3 characterized in that, upon activation of a detection sensor (Cbl-Cbn) of a given terminal (BI) becoming terminal of origin, the management unit (4) of this source terminal (BI) controls the transmission, by terrestrial telecommunication means (6), to a centralized control station (PC) also equipped with terrestrial telecommunication means , a signal comprising the identification of this source terminal (BI) and information on the abnormal conditions of circulation at the origin of the emission of said signal.   5 / A method of communication according to claim 4 characterized in that, on receipt of a signal transmitted by an original terminal (B1): É the centralized control station (PC) is adapted to control the transmission, to terminals (Bn) arranged upstream of the relay terminals (B2, B3), a signal comprising the identification of the original terminal (BI) and information on the abnormal traffic conditions at the origin of the transmitting said signal, E the management unit (4) of each of said terminals (Bn) arranged upstream of the relay terminals (B2, B3) is adapted to control the transmission, by the radiofrequency communication means (5) associated with a signal comprising information on the abnormal conditions of circulation at the origin of the emission of said signal and on the distance separating this terminal (Bn) from the original terminal (BI).   6 / A method of communication according to one of claims 1 to 5 characterized in that: E team each vehicle (V1-Vn), on the one hand, terrestrial telecommunications means (3) having an identification address of the said vehicle, and secondly sensors (Cv1-Cvn) for detecting abnormal conditions of immobilization of this vehicle, the vehicle management units (1) are programmed (V1-Vn) so as to control, when the activation of a sensor (Cv1-Cvn) for detecting an immobilization of one of said vehicles, a communication procedure adapted to deliver, to the terminal (B1) directly upstream of this vehicle, a signal comprising information concerning the presence of said vehicle and the reasons for said presence, É and programming the management units (4) of the terminals (B1-Bn) so that, on receipt of a signal representative of a immobilization of a vehicle directly downstream of a terminal (B1), the d ite terminal behaves like an original terminal.   Communication method according to claim 6, characterized in that, in order to initiate a communication procedure, when activating a sensor (Cv1-Cvn) for detecting an immobilization of a vehicle (V1- Vn), the respective management units (1, 4) of the vehicles and terminals (B1-Bn) are programmed so that an identification of each terminal is made by the management unit (1) of any vehicle passing by the said terminal.   A system for exchanging and communicating traffic information 20 characterized in that it comprises: E a plurality of terminals (B1-Bn) intended to be installed along a roadway at a distance from each other, each of said terminals being equipped with: - terrestrial telecommunication means (6) comprising an identification address of said terminal, - short-distance radiofrequency communication means (5), sensors (4) for detecting predetermined abnormal traffic conditions , such as meteorological conditions, and a management unit (4) for acquiring the data from the detection means (4), and controlling the terrestrial telecommunication means (6) and the radiofrequency communication means ( 5), each of said management units being programmed so that, when activating a detection sensor of a given terminal (BI), said terminal of origin: E the management unit of this terminalof origin (BI) controls the transmission, by terrestrial telecommunication means (6), to n terminals (B2, B3), called relay terminals, arranged directly upstream of said original terminal, with nz 1, of a signal comprising the identification of this source terminal (BI) and information on the abnormal conditions of circulation at the origin of the emission of said signal, E the management unit (4) of each of the n relay terminals (B2, B3) controls the transmission, by the associated radiofrequency communication means (5), of a signal comprising information on the abnormal traffic conditions at the origin of the transmission of said signal as well as on the distance separating this relay terminal (B2, B3) from the original terminal (BI), E a reception and information communication unit (GV) 10 intended to equip each vehicle and comprising: - means short-range radiofrequency communication device (2), for receiving the signals emitted by the radiofrequency communication means (5) of the terminals (B1-Bn), and a management unit (1) of the signals received by the radiofrequency communication means (2), programmed so that the management unit (1) of each vehicle (V1-Vn) receiving a radiofrequency signal from a relay terminal (B2, B3) controls the activation of visual and / or audible warning means of information of the driver of said vehicle.   91 A traffic information exchange and communication system according to claim 8 characterized in that it comprises a centralized control station (PC) equipped with terrestrial telecommunication means to which, during the activation of a sensor detection of a given terminal (B1) becoming original terminal, the management unit (4) of this source terminal (B1) controls the transmission of a signal comprising the identification of this terminal of origin (BI) and information on the abnormal conditions of circulation at the origin of the emission of said signal.   Traffic information exchange and communication system according to claim 9, characterized in that the centralized control station (PC) is adapted to receive a signal transmitted by an origin terminal (B1) for controlling transmitting, to terminals (Bn) arranged upstream of the relay terminals (B2, B3), a signal comprising the identification of the original terminal (BI) and information on the abnormal conditions of circulation to the origin of the emission of the said signal.   11l traffic information exchange and communication system according to one of claims 8 to 10, characterized in that: E the information exchange and communication unit of each vehicle (VI-Vn) comprises terrestrial telecommunication means (3) comprising an identification address of said vehicle, and sensors for detecting abnormal immobilization conditions of said vehicle, E the management unit (1) of each of the exchange units and of communication of information equipping a vehicle is programmed, when activating a detection sensor of an immobilization of said vehicle, to control a communication procedure adapted to deliver to the terminal (B1) directly upstream of this vehicle, a signal comprising information concerning the presence of said vehicle and the reasons for said presence, É and the management unit (4) of each terminal (B1-Bn) is programmed so that, at reception tion of a signal representative of immobilization of a vehicle directly downstream of a terminal (B1), said terminal behaves like an original terminal.