FR2930362A1 - Motor vehicle i.e. car, driver warning method for express highway, involves emitting message representing dangerous occurrence and location to reception units, and displaying alarm message on screen of display units to warn vehicle driver - Google Patents

Abstract

The method involves addressing a message representing a dangerous occurrence and a location (EE) of a road traffic lane (V1) to a communication beacon (B1) in case of detection of the occurrence in the location. Another message representing the occurrence and the location is emitted by the beacon to radio reception units (MR) of a motor vehicle (VA1). A sound alarm message e.g. speech synthesis message, is diffused with a loudspeaker (MD) in case of reception of the latter message. The alarm message is displayed on a screen of display units (MA) to warn a driver of the vehicle. An independent claim is also included for a system for warning a driver of a motor vehicle.

Description

The invention relates to the warning of motor vehicle drivers of the occurrence of a potentially dangerous event on a road lane on which they are traveling, or which is a system associated with a motor vehicle. they go along. In order to inform motor vehicle drivers of what is happening downstream of the traffic lane on which they drive or run, several solutions have been proposed. Thus, it has been proposed to equip certain traffic lanes, such as motorways or expressways, with billboards on which information messages relating to traffic (fluidity, slowing down or plugging) are displayed and / or weather conditions (strong wind, rain, snow, ice, fog, (risk of) ice) and / or the condition of the tracks (work, presence of object (s), coating deteriorated or covered with particular material locally) and / or the presence of motor vehicles (accident, breakdown, maintenance or maintenance intervention). In what follows, we call an event everything that can be the subject of an information message. This solution has at least two disadvantages. First of all, the information messages can be generated and displayed only after the corresponding event has been detected by a person or a detection device and then reported to a service (or central call center). via a communication, which can take a relatively long time during which accidents can occur because the drivers are not informed of the detected event. Moreover, it frequently happens that a driver has not read a displayed information message, for example because he has already passed the billboard preceding the event (low density of the billboards). display), or that he could not read an information message displayed on a billboard because it was hidden or he did not see it. It has also been proposed to transmit information messages to motor vehicles by waves so that they are displayed on an onboard screen. This transmission is done for example by means of the RDS (Radio Data System) technique. This solution has at least two disadvantages. Firstly, the information messages can be generated and displayed only after the corresponding event has been detected by a person or a detection device, then reported to at least one service (or call center). ) via at least one communication, which can take a relatively long time during which accidents can occur because the drivers are not informed of the detected event. In addition, it requires that the display systems of motor vehicles are activated, or even sometimes that a specific application is in use (such as the radio reception application or a satellite guidance application), That is not always the case. It has also been proposed, particularly in document FR 2799295, to equip the edge of certain traffic lanes with light warning means that are activated upstream of the location where a potentially dangerous event has been detected. by means of a communication beacon which is itself alerted by a specific service, in order to visually warn the drivers of motor vehicles. This solution has at least two disadvantages. First of all, the drivers are informed of the occurrence of an event downstream of the place where they are, but they are not informed of the type of this event. On the other hand, some drivers may not know the meaning of the lights that are emitted by light warning means that have been locally activated. The invention aims to improve the situation.

It proposes for this purpose a method dedicated to the warning of drivers of motor vehicles equipped with radio reception means and sound broadcasting means and / or display means. This method is characterized in that it consists, in the event of detection of a potentially dangerous event at a location of a first roadway: - to send to a communication beacon a first message which is representative of this event and from this place, then - to transmit, by means of the beacon and to the means of radio reception of motor vehicles which circulate at least on the first lane, a second message which is representative of the event and the place, and - in the event of receipt of the second message in a motor vehicle, to broadcast an audible alarm message with its sound broadcasting means 1 o and / or to display an alarm message with its display means, way to warn the driver of the detected event. The method according to the invention may comprise other characteristics that can be taken separately or in combination, and in particular: the audible alarm message may be a selected alarm signal; The audible alarm signal may, for example, warn the driver that an alarm message representative of the event and of the place is accessible via the display means of his motor vehicle; alternatively, the audio alarm message may be a voice synthesis message representative of the event and the location; 20 - we can automatically display an alarm message representative of the event and the location with the display means of the motor vehicle; it is also possible to transmit, by means of the beacon, to light warning means which are located at least at the edge of the first channel in a selected zone extending at least over a first distance selected upstream of the first channel. event, a third message ordering them to emit light signals; the zone chosen may also extend over a second distance chosen downstream of the event in order to warn drivers of 30 motor vehicles which are traveling on a second roadway parallel to the first lane and in the opposite direction of traffic to the latter; the third message may be suitable for ordering the light warning means to emit light signals continuously or periodically; the third message may be suitable for ordering the light warning means to emit light signals of a color chosen from at least two different colors depending on the event and / or their proximity to the location ; a beacon can be notified by means of a first message which is generated by a device chosen from (at least) an event detection device (s) implanted in a motor vehicle or in a chosen place of a lane, a mobile phone belonging to a passenger of a motor vehicle or to a person forming part of a response team, and an alarm terminal located at the edge of a traffic lane. The invention also proposes a system dedicated to the warning of drivers of motor vehicles equipped with radio reception means and sound broadcasting means and / or display means. This system is characterized in that it comprises: first devices capable of generating a first message representative of a potentially dangerous event at a location of a first roadway, at least one communication tag loaded, in the event of reception of a first message, of transmitting to the means of radio reception of motor vehicles which circulate at least on said first channel, a second message representative of this event and of this place represented in the first message received, and second devices, implanted in motor vehicles, and loaded, in the event of reception of a second message by their motor vehicle, to cause the broadcasting of an audible alarm message by the sound diffusion means of their vehicle. and / or the display of an alarm message by the display means of their motor vehicle, to warn their driver of this ment detected.

The system according to the invention can comprise other characteristics that can be taken separately or in combination, and in particular: its second devices can be responsible for causing the diffusion of a sound alarm message, of the alarm signal type; chosen, by the means of sound diffusion of their motor vehicle; its second devices may, for example, be responsible for causing the broadcast of an audible alarm signal warning the driver that an alarm message representative of the event and of the location is accessible via the display means of his motor vehicle; alternatively, its second devices may be responsible for causing the broadcast of a voice synthesis message type audible alarm message representative of the event and the location; its second devices may be responsible for causing the display of an alarm message representative of the event and of the place by the display means of their motor vehicle; each beacon can be loaded, if a first message is received, to also transmit to light warning means, which are located at least at the edge of the first channel in a chosen zone extending at least over a first distance chosen upstream of the event, a third message ordering them to emit light signals; the zone chosen may, for example, also extend over a second distance chosen downstream of the event in order to warn drivers of motor vehicles traveling on a second road parallel to the first lane and of traffic direction opposed to the latter; each beacon may, for example, be responsible for generating a third message capable of instructing the light warning means to emit light signals continuously or periodically; each beacon may, for example, be responsible for generating a third message capable of instructing the light warning means to emit light signals of a color chosen from at least two different colors depending on the event and / or their proximity to the place; its first devices can be chosen from (at least) an event detection device (s) implanted in a motor vehicle or at a chosen place of a track, a mobile telephone belonging to a passenger of a motor vehicle or to a person who is part of a response team, and an alarm terminal located at the edge of a traffic lane. Other features and advantages of the invention will appear on examining the detailed description below, and the attached drawing, in which the single figure schematically and functionally illustrates a portion of a highway and a portion of a exemplary embodiment of a warning system according to the invention. The attached drawing may not only serve to complete the invention, but also contribute to its definition, if any. The object of the invention is to provide a warning method (and the associated warning system) making it possible to warn drivers of motor vehicles very quickly of the occurrence of a potentially dangerous event on the roadway on the road. which they circulate or that they go along. In what follows, it is considered as a non-limiting example that the traffic lanes are dual lanes of highways. But, the invention is not limited to this type of pathway. It concerns in fact any type of roadway on which motor vehicles can circulate. It may also be fast roads or roads (national or departmental, or even urban). Furthermore, it is considered in the following, by way of non-limiting example, that motor vehicles are cars. But, the invention is not limited to this type of motor vehicle. It concerns indeed any type of motor vehicle authorized to circulate on a roadway. It may also be trucks, buses, buses, commercial vehicles or motorcycles. FIG. 1 shows a portion of a highway comprising a first vehicular roadway V1 divided into two parts on which motor vehicles VAi (here cars) can be driven in a first direction, and a second roadway. V2 road traffic divided into two parts on which motor vehicles VAi (here cars) can circulate in a second direction opposite to the first direction. In the nonlimiting example illustrated, cars referenced VA1 to VA3 travel on the first road (traffic) V1, and cars referenced VA4 and VA5 travel on the second road (traffic) V2. The index i therefore takes values between 1 and 5, by way of non-limiting example. The invention proposes to implement a method of warning drivers of motor vehicles VAi in the environment of a traffic lane V1 or V2 (here a highway V1-V2).

Note that for the invention can be implemented cars (or motor vehicles) VAi must be equipped with radio reception means MR and MD sound broadcasting means (such as speakers) and / or MA display means (such as a screen coupled to a man / machine interface). Note that in the example shown the display means MA are part of an interface assembly El of the car VAi which comprises the on-board computer and which is coupled to the sound diffusion means MD. But, this is not mandatory. Indeed, the sound diffusion means MD and / or the display means MA may be part of an equipment that is embedded in the car VAi and possibly provided with its own MR reception means, such as a guide equipment by satellites. It will also be noted that complementary means, such as external signaling means, can be envisaged to warn people outside a vehicle.

This warning method consists in: - addressing (at least) a communication beacon Bk a first message representative of a potentially dangerous event detected on a first roadway V1 and the place EE where this event has been detected, then - to emit, by means of the beacon Bk and to the radio reception means MR of motor vehicles VAi which circulate at least on the first channel V1, a second message representative of this event and of this location EE, and in the event of reception of the second message in a motor vehicle VAi, to broadcast a sound alarm message with its sound broadcasting means MD and / or to display an alarm message with its display means MA, in order to warn the driver of the detected event.

This method can be implemented in particular by means of a warning system S of the type which will be presented hereinafter. As illustrated, a warning system S comprises first devices D1j, at least one communication beacon Bk and second devices D2.

The first devices D1j (here j = 1 or 2) are responsible for generating a first message that is representative of a potentially dangerous event at an EE location of a (first) traffic lane V1. These first devices D1j can be implanted (or embedded) in various places depending on their type.

Indeed, several types of first devices D1j can be envisaged. Thus, it may be a detection module Dl 1 which is responsible for detecting the occurrence of events in his car VAi, such as an accident or a breakdown (or malfunction) resulting in immobilization, and, in detection of an event, to generate a first message representative of this event and the geographical position of the place EE where his car VAi is, and to order the means of radio communication of his car VAi (which include the radio reception means MR) to transmit this first message by means of waves to adjacent communication beacons Bk. In this case, the generation and transmission of a first message are automatic. It may also be mobile (or cellular) D12, or similar communicating equipment, provided with a key or menu offering an option dedicated to the warning of communication tags Bk. In this case, when a user actuates the dedicated key or selects the dedicated option of the menu, he must describe the event occurred (orally or textually), and a dedicated application of his mobile phone D12 determines the geographical position of the EE location where the latter is located then generates a first representative message of the event described and the geographical position of the place EE and orders the radio communication means of his mobile phone D12 to issue this first message by way of waves to adjacent communication Bk beacons (possibly according to a standard type Bluetooth or Wi-Fi).

Note that the mobile phone D12 may belong to a passenger of a car VAi or to a person who is part of a response team. It may also be fixed alarm terminals at selected locations of the V1-V2 motorway (accessible to users) and comprising wired or wireless means of communication (radio) capable of establishing communications with the control beacons. neighboring Bk communication (possibly according to a standard of the Bluetooth or Wi-Fi type). In this case, when a user actuates a dedicated key of an alarm terminal, he must describe the event occurred (orally or textually), and a dedicated application of the alarm terminal generates a first message representative of the alarm terminal. detected event and the geographical position (known) of the EE location where its alarm terminal is located, then orders the communication means of its alarm terminal to transmit this first message to neighboring communication tags Bk.

They may also be event detectors, which are fixedly implanted at selected locations of the V1-V2 motorway and which are coupled to wired or non-wired (radio) communication means capable of establishing communications with each other. neighboring Bk communication beacons (possibly according to a standard of Bluetooth or Wi-Fi type). These event detectors can be surveillance video cameras, or temperature and / or hygrometry detectors, or radars, or anemometers. They are capable of detecting an event, such as for example a vehicle stopped on a track V1 or V2, or an object lost on a track V1 or V2, or the presence of a material on the lining of a track V1 or V2, or a vehicle traveling in the opposite direction and / or at a very high speed, or a temperature that could lead to ice or ice on a V1 or V2 track, or a snowfall, or fog, or rain, heavy wind, or fire. In this case, when an event detector (s) has detected an event, a dedicated application that it understands generates a first message representative of the detected event and the geographical position (known) of the place EE where it is implanted, then orders the communication means to which it is coupled to transmit this first message to neighboring communication tags Bk. Each communication beacon Bk (here k = 1 or 2) is preferably located in the environment of the highway V1-V2, for example near its tracks V1 and V2, and distributed over their length. But, this is not mandatory. It can indeed be envisaged that the communication beacon (s) Bk (e) t relatively distant from the implanted pathways. Moreover, it is also conceivable to use only one communication beacon Bk for one channel or two parallel channels. Each communication beacon Bk is responsible for receiving the first messages that are transmitted (wired or wireless) by the first devices D1j and transmit (by wave (possibly according to a standard type Bluetooth or Wi-Fi )), following such a reception, a second message, which is representative of the event and the location EE which are represented in a first received message, for the radio reception means MR of cars VAi which circulate at least on the path where the event was detected, for example the first V1. When the communication beacons Bk are distributed substantially periodically along a channel, their transmission power is preferably chosen so as to ensure a transmission over a distance equal to at least twice the distance separating two consecutive communication beacons Bk. . Note that a second message may include event information identical to that contained in the corresponding first message. But, this is not mandatory. It can indeed be envisaged that the event information contained in a second message is only representative of those contained in the corresponding first message.

The second devices D2, which are the recipients of the second messages transmitted by the communication tags Bk, are preferably located in the cars VAi where they are coupled directly or indirectly to the radio reception means MR. It should be noted that a second device D2 can also be implanted in an electronic display panel provided with MR reception means. It will be understood that a second device D2 may be implanted in an interface assembly E1, as illustrated in the single figure, possibly in the on-board computer, or in equipment embedded in the car and provided with broadcasting means. MD sound and / or display means MA, as well as possibly its own MR reception means, such as a satellite guidance equipment. What is important is that the second device D2 is coupled, directly or indirectly, to radio reception means MR capable of receiving the second messages and to sound diffusion means MD and / or means for receiving the second messages. MA display (as well as possibly to additional means, such as external signaling means for warning people outside the vehicle VAi). The second devices D2 can be made in the form of electronic circuits, software modules (or computer), or a combination of circuits and software. In what follows, it is considered that the second devices D2 are coupled to the radio reception means MR and the sound diffusion means MD and / or the display means MA VAi cars they equip. Each second device D2 is loaded, when the radio reception means MR (to which it is coupled) have received a second message (representative of an event and a location EE), to cause the broadcast of an alarm message. sound by the sound diffusion means MD of his car VAi and / or the display of an alarm message by the display means MA of his car VAi, to warn his driver of this detected event. In other words, when a second device D2 receives a second message, it causes either only the broadcasting of a sound alarm message by the sound diffusion means MD of its car VAi, or only the display of an alarm message by the display means MA of his car VAi, that is to say both the broadcasting of a sound alarm message by the sound diffusion means MD of his car VAi and (or then) the displaying an alarm message by the display means MA of his car VAi. The audible alarm messages can be of two different types. It may indeed be either a selected alarm signal intended to attract the attention of the driver (such as for example a succession of beeps of a predefined tone (possibly depending on the type of event detected)), or a speech synthesis message that is representative of the detected event and the location EE. It will be noted that in the case of the triggering of an audible alarm signal, the latter may simply be intended to warn the driver that an alarm message representative of the detected event and of the location EE is accessible via the MA display means (here of his car VAi). In this case, the driver (or a passenger) must use the man / machine interface of the interface assembly El to trigger the display on the screen of the display means MA of the alarm message representative of the detected event and EE location. For example, the audible alarm signal may be broadcast until the driver has displayed the alarm message on the screen. Note that an alarm message displayed may include text and / or an image. Thus, it can be for example of the type of vehicle attention accident at kilometer 123 or attention vehicle accidented with 3 kilometers (which requires a subtraction between the geographical positions of the place EE and the car VAi) or attention vehicle accidented at the level of the city XY or slowdown in 5 km or slowdown at the exit n ° 7 or attention risk of ice in 2 km or attention foggy zone in 3 kilometers or even very strong lateral wind in 1 km. The text message may possibly be displayed on an image representing the V1 path on which the car VAi and the relative geographical positions on the car of the car VAi and the place EE where the event has been detected.

Note also that a voice synthesis sound message can contain the same words as those contained in the text message examples mentioned above. Note also that in the case where the second message only causes the display of an alarm message, it is not necessary that the display means MA is already activated. It can indeed be envisaged that upon receipt of a second message the second device D2 causes the activation of the display means MA for the immediate display of the corresponding alarm message. In order to reinforce the warning of the drivers, but also to facilitate their assessment of the distance that separates them from the location EE where the event indicated to them by a second message has been detected, it is possible to envisage using in addition ML warning light means. These are located at the edge of a path V1 to the right (or left) with respect to the direction of circulation or in the central part PC which separates the first V1 and second V2 channels (as illustrated in the sole FIGURE ). The latter case is advantageous because it allows to visually warn with the same network of light warning means ML drivers traveling on opposite lanes of traffic direction. It may indeed be useful to warn drivers of an event occurring on the lane whose direction of travel is opposite to that of the lane on which they are traveling, because it is well known that such an event on a first lane V1 is often a center of interest causing a slowdown on the second path V2 in the opposite direction to the first (V1). Light warning means ML are, for example, light-emitting diodes (or LEDs) arranged in a network. But, it could also be luminaries (possibly already installed), such as for example those that illuminate streets (roads) or certain road traffic routes.

In the presence of such light warning means ML, each communication beacon Bk is responsible for transmitting a third message, ordering the emission of light signals, at least some of those who are located at least at the edge of the path or at the event, for example the first V1, has been detected in a chosen zone which extends at least over a first selected distance d1 (or d1 + d2) upstream of the location EE where this event has been detected. It will be noted that the chosen zone, in which ML warning means must be activated, may also extend over a second selected distance d3 (or d3 + d4) downstream of the location EE where an event has been detected. (for drivers who are located on track V1 where the event has been detected) or upstream of the place EE where this event has been detected (for drivers who are located on track V2 whose direction of travel is opposite to that of the V1 channel where the event was detected).

It will also be noted that a third message may be intended to order light warning means ML to emit light signals continuously or periodically (flashing state). Moreover, a third message may be intended to order ML warning light means to emit light signals of a color chosen from at least two different colors (for example red or orange) as a function of the detected event. and / or their proximity to the EE location where the event was detected. For example, an orange color can be used to signal an event that is still relatively distant (for example, located at a distance of between 3 km and 6 km), whereas a red color can be used to signal a nearby event (for example located at a distance between 0 m and 3 km). The distance at which a light warning is issued may vary from one type of lane to another, particularly depending on the speed limits in force.

In the nonlimiting example illustrated in the single figure: - the black circles materialize light warning means ML activated to operate in a first color, for example red, and for example continuously, because they are placed at a distance less than or equal to dl or d3 and therefore (very) close to the event detected at the location EE on the first channel V1. This event is for example a breakdown of the car VA3 which was automatically detected by its first device Dl type 1 (onboard event detector), - the gray circles materialize light warning means ML activated to operate according to a second color, for example orange, and for example periodically, because they are placed at a distance greater than dl (or d3) but less than or equal to dl + d2 or (d3 + d4) and therefore relatively far away of the event detected at the location EE 1 o on the first channel V1, - the white circles materialize light warning means ML not activated because placed at a distance too far from the event detected at the location EE on the first way V1. A third message may be transmitted by a communication beacon Bk to light warning means ML wired or wireless (possibly according to a Bluetooth standard or Wi-Fi). Each light warning means ML or each group of light warning means ML must therefore be coupled to a reception means, possibly of radio type. For example, each light warning means ML or each group of light warning means ML is capable of determining according to the content of the third message and in view of its position with respect to the location EE where the event has been detected if it should be activated and possibly the color that it should use as well as the mode of operation (flashing or continuous) corresponding. As a variant, it can be envisaged that the communication terminal Bk sends to each light warning means ML or to each group of light warning means ML that it wishes to activate a third specific message which possibly describes to it the color that it must use as well as the mode of operation (flashing or continuous) corresponding.

Thanks to these additional ML warning light means, the drivers are not only informed inside their car VAi by an audible alarm message and / or an alarm message displayed, but also outside the car. their car VAi by lights whose eventual colors and / or modes of operation are representative of the distance that separate them from the place EE where an event has been detected. For example, the deactivation of the ML warning light means may be controlled exclusively by the persons who belong to an intervention service (for example of emergency service), once the event has disappeared (for example once a car has been turned off). VAi has been repaired or the end of a strong wind or a risk of ice has been noted). This deactivation can for example be done by transmission of a dedicated message. Thanks to the invention, all drivers of motor vehicles that are located in an area close to a potentially dangerous event can be warned very quickly of this event (because it does not go through a central call), thus allowing significantly reduce the risk of accidents due to the effect of surprise and / or lack of vigilance. The invention is not limited to the warning system and warning method embodiments described above, by way of example only, but encompasses all the variants that can be envisaged by those skilled in the art. within the scope of the claims below.

Claims (12)

REVENDICATIONS1. A warning method for drivers of motor vehicles (VAi) equipped with radio reception means (MR) and sound diffusion means (MD) and / or display means (MA), characterized in that it consists, in the event of detection of a potentially dangerous event at a location (EE) of a first traffic lane (V1), i) to send to at least one communication beacon (Bk) a first message representative of said event and said (EE), ii) and then to transmit, by means of said beacon (Bk) and to the radio reception means (MR) of motor vehicles (VAi) which circulate at least on said first channel (V1), a second message representative of said event and said location (EE), and iii) when receiving said second message in a motor vehicle (VAi), to broadcast an audible alarm message with its sound diffusion means (MD) and / or display an alarm message with its display means (MA) in order to warn the driver of said detected event. 2. Method according to claim 1, characterized in that said audible alarm message is a selected alarm signal. 3. Method according to claim 2, characterized in that said audible alarm signal is able to warn the driver that an alarm message representative of said event and said location (EE) is accessible via said display means (MA ) of his motor vehicle (VAi). 4. Method according to claim 1, characterized in that said audible alarm message is a voice synthesis message representative of said event and said location (EE). 5. Method according to claim 1, characterized in that one automatically displays an alarm message representative of said event and 3o said location (EE) with said display means (MA) of the motor vehicle (VAi). 6. Method according to one of claims 1 to 5, characterized in that it is also transmitted by means of said beacon (Bk) and to destination light warning means (ML) located at least on the edge of said first channel (V1) in a selected area extending at least a first distance selected upstream of said event, a third message ordering them to emit light signals. 7. The method as claimed in claim 6, characterized in that said selected zone also extends over a second distance chosen downstream of said event so as to warn motor vehicle drivers (VAi) who are traveling on a second parallel roadway. to said first channel (V1) and the opposite direction of the latter. 8. Method according to one of claims 6 and 7, characterized in that said third message is adapted to order said light warning means (ML) to emit continuous light signals. 9. Method according to one of claims 6 to 8, characterized in that said third message is adapted to order said light warning means (ML) to emit light signals periodically. 10. Method according to one of claims 6 to 9, characterized in that said third message is adapted to order said light warning means (ML) to emit light signals of a color chosen from at least two different colors. according to said event and / or their proximity to said location (EE). 11. Method according to one of claims 1 to 10, characterized in that a beacon (Bk) is notified by means of a first message generated by a device selected from a group comprising at least one detection device. event (s) (D11) implanted in a motor vehicle (VAi), an event detection device (s) located in a chosen location of a track, a mobile telephone (D12) belonging to a passenger of a vehicle automobile (VAi), a mobile phone belonging to a person belonging to a response team, and an alarm terminal located at the edge of a traffic lane. 12. Warning system (S) for motor vehicle drivers (VAi) equipped with radio reception means (MR) and sound diffusion means (MD) and / or display means (MA), characterized in that it comprises i) first devices (D1j) capable of generating a first message representative of a potentially dangerous event at a location (EE) of a first roadway (V1), ii) at least one communication beacon (Bk) arranged, in the event of reception of a first message, for transmitting to the radio receiving means (MR) of motor vehicles (VAi) which circulate at least on said first channel (V1), a second representative message of said event and said location (EE) represented in said first received message, and iii) second devices (D2), implanted in said motor vehicles (VAi), and arranged, in case of receipt of a second message by their motor vehicle ( VAi), for provoq uer the broadcasting of an audible alarm message by the sound diffusion means (MD) of their motor vehicle (VAi) and / or the display of an alarm message by the display means (MA) of their motor vehicle (VAi), so as to warn their driver of said detected event.