DE69015662T2 - Vehicle traffic and parking information system, in particular for motorists. - Google Patents

Abstract

This system comprises: - information-collecting means (100) for gathering and centralising a set of information relating to the state of the traffic in a given zone, in particular an urban zone, each item of information corresponding to a segment included between two predetermined characteristic sites, - means (210) for transforming this set of information into a series of elementary digital information each consisting of an identifier of segment and of direction of flow and of a state variable representing the state of traffic of this segment in the said direction of flow; - means (220) for formulating, on the basis of this series of digital information, a scrolling, continuous and cyclic sequence of information consisting of the elementary digital information from all the relevant segments, this sequence being regularly updated as a function of the change in the information gathered; - means (330, 340, 350) for broadcasting this scrolling sequence of information over the air; and - on board the said vehicles: means (360) of receiving the said scrolling sequence of information thus broadcast, discriminator means (240) for selecting, from the set of elementary information, that likely to interest the driver, as a function of a predetermined criterion inserted by the latter; and means for presenting the driver with the elementary information thus picked out. <IMAGE>

Description

The present invention relates to a system and a method for collecting and disseminating information on traffic movement and parking of transport vehicles, particularly intended for motorists.

It is common practice to broadcast messages during radio broadcasts to alert drivers to traffic difficulties (traffic jams, accidents, etc.) on certain roads or at certain traffic junctions in a metropolitan area.

This information can only be limited in quantity and specific to the driver, who receives all the messages thus transmitted without distinction. The device described in EP-A-290 679 receives a large amount of traffic information and allows the messages relating to an area of interest to the user to be selected, but does not solve the problem of gathering information and cannot provide personalized guidance information.

For this reason, specific guidance systems have recently been developed that provide each driver with personalized information about the route he must follow, indicating any relief routes that allow him to determine his position in the city, etc.

In particular, mention should be made of the system developed by Siemens AG in collaboration with the University of Berlin and Robert Bosch GmbH under the name Alescout, which is based on a system for the bidirectional exchange of data by infrared rays between the vehicles to be guided and beacons placed at various intersections.

When approaching an intersection and receiving an interrogation signal emitted by the beacon of that intersection, the vehicle's transponder transmits the information received from the sensors of that vehicle to the beacon. This information is then sent by the beacon to a central computer which compares the information with similar information sent by the same vehicle to the previous beacon and determines the fluidity of the traffic and any deviation of the actual path of the vehicle from the path initially planned.

In response, the server center sends guidance information back to the beacon, which is then transmitted from the beacon to the vehicle. This guidance information appears, for example, on a screen in the form of an arrow that indicates to the driver the direction to take in order to reach the next beacon on his route (or the next beacon on a relief route if the server center has determined that this would be preferable); and that indicates the distance to the beacon from a bird's eye view.

Such a system is described, for example, in the document entitled (see LISB Control and Information System Berlin - ALISCOUT in large-scale field trial, published by Siemens AG and reference number A 1900-N9-11, as well as in the publications EP-A-0 029 201 and EP-A-0 292 897.

Of course, such a system, although effective, is extremely laborious and expensive to install. The following must be taken into account:

- From the point of view of the ground infrastructure, in particular because of the increased density of crossing beacons required for the satisfactory operation of the system in an urban environment, it is necessary to install a system that is completely new (without the possibility of reusing the often existing installations, such as the systems already in place designed to regulate traffic by synchronising the three-colour traffic lights) and without the possibility of progressive installation, which entails very significant investments for the community.

Furthermore, the system requires a significant number of bidirectional connections both between beacons and vehicles and between beacons and the server center. The increase in the number of crossing beacons therefore requires a corresponding expansion of the size of the network, which limits the possibilities for rapid generalization of the system due to the costs and complexity that such an infrastructure entails.

- With regard to the equipment carried by each of the vehicles wishing to participate in the system, they must all be equipped not only with an infrared transmitter/receiver and a certain number of sensors that allow the system to track their movements, but also a complicated interface that allows the driver to be guided through a screen and a voice synthesizer. This complete set of features represents a significant cost factor as individual equipment.

Finally, it appears that there is a potential clientele of drivers who simply wish to use precise and personalized information on the state of traffic on the route they wish to take; and they wish to do so in order to adapt or modify that route, taking into account the knowledge they already have of the location, without having to submit themselves to automatic guidance over which they are not in control.

The invention aims to eliminate these drawbacks of the above-mentioned system by proposing an information collection and dissemination system that:

- to collect information, as a complement or as a variant of the above-mentioned system, other existing techniques and systems of data collection are used - in particular the systems already installed designed to regulate traffic by synchronising three-colour traffic lights; and that it

- for the dissemination of information, it makes it possible to propose to a large audience of users the dissemination of information through an adapted channel, complementing the land route of those subscribers who have chosen this system.

In fact, as will be seen later, the system according to the invention, although simplified in comparison with the known system mentioned above, can be installed at a reasonable cost in any vehicle wishing to use the information generated and disseminated by the system according to the invention. In addition, as will also be explained later, the increase in the number of vehicles does not entail an increase in the transmission capacity of the network connected to the server center.

Nevertheless, as will be explained below, the driver, equipped with a receiver for the information disseminated by the system according to the invention, can be informed of the state of traffic on the entire route he intends to take, and in particular on that route alone - and also, as the case may be, on the adjacent areas of that route.

The fact that information is presented to the driver selectively depending on the route he has chosen makes it possible to provide very detailed information (for example, the metropolitan area is divided into 1000 sections or characteristic locations for which the traffic situation can be individually ascertained), but only the information that is of interest to the driver based on his route is provided, for example the information relating to around 10 or 15 sections or characteristic locations.

For this purpose, the system according to the invention has the features mentioned in claim 1. The invention also covers a corresponding method, which is the subject of claim 12.

The information collection devices can, for example, include the Aliscout system mentioned above. In this case, however, only a limited number of vehicles will be equipped (hereinafter referred to as "flying vehicles") and will serve as reference vehicles and will be part of the permanently circulating vehicles (taxis, buses, delivery vehicles, public service vehicles, etc.). It is therefore possible to:

- either use the complete system described above, which makes it possible to provide guidance to the flying vehicles, which are by nature the vehicles for which guidance is most useful, or use only the simplified system, with a unidirectional connection of the beacon and without a system for decoding and displaying the guidance information on board the vehicles. Such a simplified system would only provide the function of analyzing traffic by tracking the flying vehicles, which is necessary but also sufficient for the implementation of the system according to the invention.

Advantageously, the continuous sequence of information is transmitted by radio by a method for transmitting digital data with a subcarrier added to the broadcast signal, the receivers on board the vehicles being radio receivers equipped with a decoder which separates the information of the digital signal from the audio program signal.

One can use the RDS (Radio Data System) system for transmitting digital data by radio with frequency modulation, the specifications of which are defined by the European Union of Radiocommunications, and these specifications are mainly used in Document reference Tech. 3244 published by that organization in March 1984.

The specifications of the RDS system provide, in addition to the transmission of a certain amount of standard information (type and name of the station, other frequencies of the same program, time and date, radio text information), the possibility of having "data channels for external use" which enable the transmission of messages of any length and format, as well as the transport of alphanumeric characters and any other digital data.

The reception of traffic information messages by the RDS system is described, for example, in the documents EP-A-0 290 679, EP-A-0 263 332 or EP-A-0 300 205.

The advantage of the RDS system is that it can be used by simple car radios equipped with a decoder, and various models of these devices are currently available or under development. To use the control information of the invention, it is therefore sufficient to connect a box containing the appropriate circuits and control devices to the digital data output of the car radio.

Compared to a control system such as the Aliscout system mentioned above, this simultaneously eliminates the need for the specific data transmission system (which in the case of the invention is an existing FM radio transmitter, where it is sufficient to encode the signal to be transmitted in an appropriate manner) and the specific receiver on board the vehicle, which can be a simple car radio with an RDS decoder.

As an alternative, you can use other radio frequencies instead of using the carrier frequency of one or more radio stations.

Further advantageous features are the subject of the subclaims.

A detailed example of an embodiment of the invention will be described below with reference to the accompanying drawings.

Fig. 1 is a block diagram of the system according to the invention showing the various functions employed; and

Fig. 2 is a representation of the route chosen by the driver and the characteristic locations surrounding this route.

In Figure 1, reference numeral 100 indicates the information collection system which, as indicated above, consists of the combination of a complete or simplified Aliscout type system with loop-based systems for regulating traffic by synchronizing the three-color traffic lights.

The system essentially comprises a set 110 of elements installed on board the flying vehicles (i.e. those as defined above, i.e. reference vehicles in a limited number selected from among the vehicles in constant circulation); beacons 120 installed at a certain number of locations; and a central server 130 which centralizes and processes the information received from the beacons.

The elements 110 carried on board the flying vehicles essentially comprise an on-board computer 111 which receives the signals coming from an electronic compass 112, which provides the absolute orientation of the vehicle relative to the magnetic north pole, and the signals coming from an odometer 113, which counts the number of revolutions of the wheels (i.e. the distance travelled) since the last beacon. A keyboard 114 enables the entry of a certain number of pieces of information, such as a vehicle registration number, which is required to locate and track a vehicle from one beacon to another.

The computer 111 is connected to an infrared transponder 115, which receives an interrogation signal from the beacon 120 and, upon receipt of this interrogation signal, sends the values measured by the sensors to the beacon.

Each beacon 120 has an infrared transmitter-receiver 122, which is mounted, for example, on a three-color traffic light 121 and exchanges information with the vehicles of the system, as well as a computer 123, which controls this information exchange and ensures the interface connection with the central server 130.

The central server 130 also enables the calculation of the route (block 131) when using the specific guidance options (which are not necessary for the implementation of the invention) of the flying vehicles by retransmitting information via the beacon, as well as the analysis of the traffic based on the information received, with possible visualization (block 132).

In a manner characteristic of the invention, the information generated by block 132 is used to create elementary digital information representative of the state of traffic at each characteristic location of the metropolitan area.

The term "characteristic locations" refers to various places in the metropolitan area that:

- either define a directed section (a vector defined by its two characteristic origin and end points) for which the state of the traffic of vehicles is a decisive piece of information for the regulation of this traffic, typically involving traffic arteries (avenues, boulevards, expressways) or sections of arteries,

- or, possibly, parking areas whose occupancy status (occupancy rate) by vehicles is information determining the regulation of traffic.

The selection of the characteristic locations and the sections is carried out in such a way that a complete network of the metropolitan area is created, while at the same time the quasi-totality of the possible routes is described simply and unambiguously.

It is estimated that for a metropolitan area such as Paris, around 1,000 sections and parking areas should allow the state of traffic to be expressed in a sufficiently comprehensive and detailed manner.

It is important to provide an indication parameter for the direction of traffic, either by using, for example, a specific coding bit or by designating the section by its two ends, the direction then being determined by the order in which the two ends are quoted (AB corresponds to one of the two directions and BA to the other).

Traffic can be fluid in one direction and congested in the other, so that if one does not distinguish between the traffic directions, one provides the driver with information that does not correspond to the actual situation.

Each directed section (or each characteristic location in the case of a parking area) is assigned a "state variable", which is information representative of the traffic state of this section (or of the level of occupancy by vehicles in the case of a parking area).

To determine this "traffic state", a certain number of classes of deceleration level are defined, expressed in relative terms of travel time over the section in question. The state variable is therefore the digital information identifying the class to which the actual deceleration level belongs, i.e. the one calculated at the time in question from the various information collected upstream.

At a minimum, one could encode only the state variable by a single bit (which would give two states: liquid/overflowing); but it is preferable to encode it by a larger number of bits, for example two or three bits, which makes it possible to provide more nuanced information (four possible states through two bits, eight possible states through three bits, etc.).

For example, if the travel time in total fluidity (minimum travel time taking into account the speed limits, the sequence of traffic lights, etc.) is tm minutes for the directional section under consideration, the following five speed reduction classes can be defined:

- "fluid": for a relative deceleration level between 0 % and 10 % (i.e., for an actual travel time between tm and 1.10 tm;)

- "tight": for a relative deceleration level between 10 % and 50 % (i.e., for an actual travel time between 1.10 tm and 2 tm);

- "slowed down": for a relative deceleration level between 50% and 75% (i.e., for an actual travel time between 2 tm and 3 tm);

- "congested": for a relative deceleration level exceeding 75 % (i.e., for an actual travel time exceeding and 3 tm); and

- "undetermined": if it is not possible to determine the level of deceleration or if the value determined for that purpose is subject to such uncertainty that the value is no longer significant.

Of course, the digital values given above are purely illustrative. It should also be noted that they are not necessarily the same for all road networks, but that, on the contrary, it may be advantageous to assign values to the respective speed reduction levels depending on the section in question, typically depending on the topography of the section and the type of road in question (expressway or road with junctions).

Furthermore, for practical reasons and in order to avoid instability of the data, the effective values of the thresholds thus determined may be reduced by 10 % in the event of increasing congestion and increased by the same amount during a period of return to normality.

The state variable will then be a digital information indicating the deceleration class to which the actual deceleration level present in the time period under consideration belongs; for example:

- '001' for the class "liquid";

- '010' for the class "tight";

- '011' for class "slowed;

- '100' for the class "clogged"; and

- '101' for the class "unspecified".

As can be seen, in each of the cases the state variable is determined exclusively as a relative value, i.e., although it is a quantitative variable, it is never provided to the driver in the form of a travel time, but in the form of a relative value relating to the degree of flow (fluidity of the traffic ("fluid", "dense", "slowed", "congested")), i.e. in the form of the only value that is easily and immediately understandable to the driver.

It can also be seen that the state variable is very advantageously always given an unambiguous value, even if the information to which it corresponds has not been able to be determined. This makes it possible to detect on board the vehicle the existence of a reception anomaly and to immediately signal to the driver if, for example, a value such as '000' is obtained at the output.

If the state variable is to represent the occupancy status of a parking area with a capacity of C vehicles, one could, for example, choose from the following digital values:

- '001' for an actual occupation between 0 and 0.2 C;

- '010' for an actual occupation between 0.2 C and 0.7 C;

- '011' for an actual occupation between 0.7 C and 0.9 C;

- '100' for an actual occupation between 0.9 C and C; and

- '101' with an unknown actual cast.

As in the case of the speed reduction classes, from a practical point of view and in order to avoid instability of the data, the actual values of the thresholds thus determined could be reduced by 10 % in the event of increasing congestion and increased by the same amount during a period of return to a normal situation.

The state variables just defined can be obtained from various sources:

- Analysis of the traffic movements of the flying vehicles through the assembly 100 described above and shown in Figure 1, where the placement of the beacons 120 may possibly correspond to that of a certain number of characteristic locations,

- magnetic sensors used to control traffic lights,

- Counting of entrances/exits to the parking facilities,

- cameras; information sent by police vehicles; etc.

To simplify the creation of the information in block 210, it is desirable to receive this information from a system that is as automated and homogeneous as possible.

This is the reason why it is preferable to choose to receive most of this information from beacons that interrogate hovering vehicles. Nevertheless, the system concludes according to the Invention does not exclude the use of other forms of data collection as a variant or as a supplement.

Block 210 creates, in the manner described, a sequence of elementary digital information, each of which consists of an identifier of the directed sub-path and a state variable, as defined above.

Preferably, it is possible to manually adjust the value of certain state variables, for example using a data acquisition console 230, in order to intentionally influence the course of traffic movement, regardless of the state of the traffic. A typical case is that in which it is desired to clear an intersection by diverting the vehicles which wished to cross it.

Therefore, additional values are provided for the state variable, for example:

- '110' for "to be avoided"; or

- '111' for "forbidden".

It should be noted that in these last cases the state variable no longer represents a calculated value that reflects an actual situation (deceleration rate), but is information set arbitrarily by the command station.

The block 210 can also weight the information it creates depending on a certain number of parameters in order to to adapt the information disseminated to the circumstances or to anticipate a possible development.

Weighting factors may include the following:

- the degree of development of the state variable between its current value and its previous value,

- the value of the state variable on the previous day at the same hour (taking into account holidays, non-working days, etc.),

- the value of the state variable of the same day of the previous year,

- the value of the state variables of certain adjacent sections and/or characteristic locations (in order to anticipate chain reactions, for example in the event of an accident at a point on a traffic artery).

The elementary digital information created by block 210 is then compiled (block 220) to create an "information segment" consisting of the totality of the elementary digital information of all the consecutive sections of the metropolitan area (as well as the characteristic locations of the same, corresponding to the parking areas from which it is desired to disseminate the occupancy status).

The segment thus created then becomes a continuous and cyclical sequence of information, which is then subject to coding, preferably the RDS coding mentioned above.

The type of modulation used in the RDS system is a two-sideband amplitude modulation with carrier suppression of the two-phase signals with differential coding. Such coding allows, for a total transmitted throughput of 1187.5 bits per second, a useful information throughput of 730 bits per second for all the information transmitted, 80 bits per second being reserved for the external use data channel, which is a channel used by the present invention to transmit the control signals.

During its run, the segment is updated, whereby the periodicity of the run then corresponds to the periodicity of the update.

In the example of 1000 sections of road and parking areas cited above, if a state variable with 10 positions is chosen, it is possible to encode the elementary digital information on 16 bits which, once grouped, form a segment of 16,000 bits. If we take into account that the RDS coding allows a useful information throughput of 80 bits per second, we can obtain a system transit periodicity (and therefore of information updating) of 200 seconds, i.e. 3' 20", a value that is entirely compatible with effective management in a metropolitan area, even in the presence of very rapidly evolving traffic conditions.

Of course, these values are given only as examples. Taking into account special cases, and limiting the maximum throughput allowed by the data transmission system, a compromise must be sought between:

- the number of sections and parking areas,

- the number of positions of the state variables, and

- the periodicity of the segment.

The thus encoded segment of elementary digital information is transmitted through a broadcast chain comprising transmitters 310 to 350 and a receiver 360 in each vehicle.

During transmission, each audio signal coming from a registration control room (block 310) is transformed in a conventional manner into a modulation signal (block 320), for example with a stereo coding with a pilot frequency. The audio signal is then multiplexed (block 340) with the signal coming from the RDS encoder (block 350), for example on a subcarrier of 57 kHz (third harmonic of the subcarrier of the stereo pilot signal of 19 kHz).

The signal multiplexed in this way is transmitted to a frequency-modulated radio transmitter 330 of known type.

Furthermore, the various vehicles are equipped with 360 receivers, which are car radio receivers equipped with conventional RDS decoders.

The digital output of the data channel for external use of the RDS 360 receiver is connected to a housing 240 specific to the invention, which thus continuously receives from this output the continuous sequence of information sent by the system.

The elementary digital information is decoded and presented to the driver in a visually readable manner on a screen and/or through speech synthesis devices 260.

However, the driver is not presented with all of the information broadcast.

Indeed, given the significant number of sections and parking areas (approximately 1 000 in the example considered) and the relatively high frequency (3.2 minutes) of the route, the driver would hear a continuous stream of messages and would find it difficult to listen and retain only those messages that interest him, at the expense of attention that would be detrimental to his safety.

The housing 240 therefore contains discrimination devices which select only those items of elementary digital information which are likely to be of interest to the driver, based on one or more predetermined criteria which are entered by the driver using a keyboard 250.

In this way, the significant messages are selected and only these significant messages are demodulated.

The predetermined criterion may in particular concern a route entered by the driver directly on the keyboard 250 (or chosen indirectly from the information entered by the driver, as explained below), based on a map showing the various characteristic locations of the agglomeration and their identification code (the code to be entered on the keyboard) are clearly displayed.

For example, the driver can enter the route ABCDE (Figure 2).

In this case, the housing 240 checks the route identifier of this information for each received elementary digital information and only communicates the corresponding state variable to the driver if this partial route identifier corresponds to the previously selected route (i.e., in the case of the example shown, only the state variables of the successive partial routes AB, BC, CD and DE are communicated).

The driver therefore only receives the messages that are relevant to him, i.e. in the case of the example shown, four messages out of a total of around 1000 messages received.

It is possible to provide for a certain number of variants or improvements:

- saving several previously created routes, which are recalled with a simple touch of the finger;

- coding several alternative routes for one and the same origin/destination pair, whereby the driver can check these routes one after the other;

- the incorporation of variants into a given route, which are issued at the same time as the route itself;

- isolated query of a given section of the route or a given parking area.

In addition, it is possible to provide for the transmission not only of information relating to the sections of the selected route (in the example shown: ABCDE), but also to adjacent sections (marked by black dots in Figure 2), with the white dots corresponding to characteristic locations marking the sections for which no information is provided to the user.

In this way, a more or less wide "corridor" is defined around the route, whereby the width of this corridor depends on the number of intermediate points between the origin and the destination that the user has assigned to the device.

By providing the driver with information relating to the chosen route and his immediate surroundings, possible deviations from the intended route during the journey can be taken into account.

Claims (21)

1. System for collecting and disseminating information on the traffic movement and parking of transport vehicles, in particular for motorists, comprising: - information collection devices (100) for receiving and centralizing a set of information relating to the state of traffic in a given zone, in particular in an urban zone, this zone being circumscribed by a network of sub-routes extending between predetermined characteristic pairs of locations, the information of this set of information corresponding to a respective sub-route: - means (210) for converting the set of information into an elementary sequence of digital information, each of which consists of an identifier for the section and the direction of traffic on that section and of a variable state representative of the traffic state on that section in the said direction of traffic; - means (220) for generating a continuous and cyclically running information sequence from the sequence of elementary digital information, consisting of elementary digital information of all possible sections, this sequence is regularly updated depending on the evolution of the information received; - means (330, 340, 350) for distributing this passing information sequence by radio; and - on board said vehicles: reception means (360) for receiving the passing information sequence thus distributed; discrimination means (240) for selecting from the totality of the elementary digital information in the passing information sequence thus received, the information which is likely to interest the driver in accordance with a predetermined criterion entered by him; and means for presenting to the driver the elementary information thus discriminated; the system being characterized in that: - the information collection means (100) comprise transmitting and/or receiving beacons (120) which interact with transponders (115) installed on board a subset of reference vehicles which form a sample of the totality of vehicles taking part in traffic and are provided with means which serve to transmit back to the beacons, through the transponders, information on their progress in the said zone and/or information coming from sensors (113 or 112), on the distance travelled (113) and/or on the orientation (112); and that the system can optionally also collect information coming from magnetic sensors used to control the traffic lights and/or counting devices used to count the entries/exits into and out of the parking facilities, and/or cameras; and/or the information transmitted by the police vehicles; and that - the means (210) for converting the totality of the collected information into an elementary digital information sequence determine from this information, for each section and each direction of travel concerned, corresponding travel times (tm) from which corresponding state variables are created. 2. System according to claim 1, in which said state variable is a digital data ('001', '010', '011', '100') which designates, among a multiplicity of classes of the deceleration level ("fluid", "dense", "slow", "clogged"), the class to which the actual deceleration level of the section in question and the direction of travel in question belongs at a time in question, the deceleration level being a relative level (x tm, with x ≥ 1) expressed in relation to the travel time (tm) existing for the section in question and the direction of travel in question in an overall fluidity situation. 3. System according to claim 2, in which the subdivision of the classes depending on the speed reduction levels is a gradation that is adaptive and variable depending on the relevant section of the route and the relevant direction of travel, in particular depending on the topography of the route and the corresponding type of traffic route. 4. A system according to claim 2, wherein the division of classes depending on the speed reduction levels is a variable division depending on the increase in the congestion state of the traffic. 5. A system according to claim 2, wherein if the actual deceleration level is indeterminate or insignificant, a predetermined, unambiguous value ('101') is assigned to the state variable. 6. System according to claim 1, in which the information collection means comprise means for transmitting information about the occupancy status of parking areas belonging to certain characteristic locations, the associated status variable in this case being a digital data item ('001', '010', '011', '100') which, among a plurality of occupancy level classes, designates the class to which the actual occupancy level of the characteristic location in question belongs. 7. System according to claim 6, wherein the occupancy level is a relative level (x C, with x ≤ 1) expressed in relation to the capacity (C) of the parking area. 8. System according to claim 6, in which the division of the classes depending on the occupancy level is an adaptive, variable division depending on the increase in the congestion state of the park. 9. A system according to claim 1, wherein means are provided for setting the value of the state variables to one or more predetermined values (“to be avoided”, “forbidden”), regardless of the traffic situation. 10. System according to claim 1, in which the continuous sequence of information is transmitted by radio using a method for distributing digital data with a subcarrier added to a broadcast signal, the receivers (360) located on board the vehicles being radio receivers equipped with a decoder which causes the information of the digital signal to be separated from the audio program signal. 11. System according to claim 1 or claim 6, in which the predetermined criterion according to which the discrimination means operate comprises a route consisting of a sequence of sections (AB-BC-CD-DE) determined from the selection data previously entered by the user, the discrimination means selecting only those elementary digital information items corresponding to the sections and/or the characteristic locations of this route and, possibly, the sections and/or the characteristic locations adjacent to this route. 12. Method for collecting and disseminating information on the traffic and parking of transport vehicles, in particular for drivers, characterized by the following steps, consisting of: (a) describing a zone, in particular an urban zone, by a route network extending between predetermined characteristic pairs of locations; (b) receiving and centralising a set of information relating to the state of traffic in that given zone, each of the pieces of information corresponding to a respective sub-route, the information being received by the transmitting and/or receiving beacons interacting with the transponders installed on board a sub-population of reference vehicles, which is a sample of the totality of the vehicles taking part in traffic, and equipped with means for transmitting back to the beacons, through the transponders, information on their progress in that zone and/or information coming from sensors on the distance travelled and/or on the orientation; and that the system can optionally also collect information coming from magnetic sensors used to control traffic lights and/or counting devices used to count entries/exits into and out of parking facilities, and/or from cameras: and/or information transmitted by police vehicles; and (c) converting that set of information into an elementary sequence of digital information, each of which consists of an identifier for the section and the direction of traffic on that section and of a variable state representative of the traffic state on that section in that direction, expressed in the form of a respective travel time; (d) generating a continuous and cyclical sequence of continuous information consisting of elementary digital Information on all relevant sections, this sequence being updated regularly depending on the evolution of the information received; (e) disseminating this continuous information sequence by radio; and (f) on board the vehicles: receiving the continuous information sequence thus disseminated; selecting from all the elementary digital information in the continuous information sequence thus received, the information which is likely to be of interest to the driver in accordance with a predetermined criterion entered by him; and presenting the elementary information thus discriminated to the driver. 13. Method according to claim 12, in which the said state variable is a digital data item ('001', '010', '011', '100') which, from a plurality of classes of the speed reduction level ("fluid", "dense", "slow", "congested"), designates the class to which the actual speed reduction level of the relevant route and the relevant direction of travel belongs at a given time. 14. Method according to claim 13, in which the speed reduction level is a relative level (x tm, with x ≥ 1) expressed in relation to the travel time (tm) existing for the relevant leg and the relevant direction of travel in a situation of unrestricted traffic fluidity. 15. Method according to claim 13, in which the subdivision of the classes depending on the speed reduction levels is an adaptive and variable gradation dependent on the relevant section of the route and the relevant direction of travel, in particular depending on the topography of the route and the corresponding traffic route type. 16. A method according to claim 13, wherein the division of the classes depending on the speed reduction levels is a variable division depending on the increase in the congestion state of the traffic. 17. A method according to claim 13, wherein if the actual deceleration level is indeterminate or insignificant, a predetermined, unambiguous value ('101') is assigned to the state variable. 18. Method according to claim 12, in which a step is provided which consists in transmitting information relating to the occupancy status of the parking spaces belonging to certain characteristic locations, the associated state variable in this case being a digital datum ('001', '010', '011', '100') which designates, among a plurality of occupancy level classes, the class to which the actual occupancy level of the characteristic location in question belongs. 19. Method according to claim 18, wherein the occupancy level is a relative level (x C, with x ≤ 1) expressed in relation to the capacity (C) of the parking area. 20. The method of claim 18, wherein the division of the classes depending on the occupancy level is an adaptive, variable division depending on the increase in the parking congestion state. 21. Method according to claim 12, in which a step is provided for increasing the value of the state variable to one or more predetermined values ("to be avoided", "prohibited"), regardless of the traffic state.