EP2162871B1 - Method and device for detecting traffic jams - Google Patents

Abstract

The invention relates to a method for detecting traffic probes on one or more driving lanes (1). It is characterised in that the lane (1) is confined into a reduced capacity area (A), a first area (B) upstream for area (A), a second area (C) upstream from area (B), and in that it comprises determining over a period (T) the speed spectrum (V) of the vehicles on the lane (1) in each of the areas (A, B, C) using an acquisition means (3), calculating in real time the average speed (VM) in each of the areas using an analysis means (4) to which said speeds (V) are communicated via local communication means (5), comparing said average speed to a first threshold (VB) and a second threshold (VH) in said area using the analysis means (4), and triggering a congestion alarm if the average speed (VM) is lower than the first threshold (VB). The invention further relates to a mobile device for implementing said method.

Description

The present invention relates to a method of detecting road closures on one or more lanes at a site. Such a process is known from the document FR-A-2,721,717 .

It also relates to a mobile device and autonomous energy implementation of this method.

The present invention is in the field of real-time management of traffic on road infrastructure, especially on motorways.

The invention relates more particularly to the detection and prevention of traffic congestion on these road infrastructures, particularly in work zones.

• une équipe mobile de sécurité routière, ou de gendarmerie, ou analogue, se rend sur les lieux de l'incident, et procède à un balisage de signalisation en amont;
• un poste de commande centralisé génère l'activation de signaux lumineux clignotants au niveau de bornes d'urgence implantées à demeure sur les voies à une distance constante entre elles, et affiche des messages ad hoc sur des panneaux d'information en texte implantés à demeure sur les voies, voire diffuse des messages sur des émetteurs radio accessibles aux automobilistes.

The safety of road infrastructures is usually managed in different ways, after signaling an incident by a surveillance agent or a user:

• a mobile team of road safety, or gendarmerie, or the like, goes to the scene of the incident, and carries out signage upstream;
• a centralized control station generates the activation of flashing light signals at emergency terminals permanently installed on the tracks at a constant distance from each other, and displays ad hoc messages on permanently installed text information panels on the channels, or even broadcasts messages on radio transmitters accessible to motorists.

It is important to be able to detect the stop of vehicles, as well as an abnormal slowdown, index of a latent problem. In particular this problem arises in work areas, often synonymous with narrowing of lanes and traffic disruption. It is not conceivable to equip work zones, which by their nature are mobile, with fixed installations for the detection and prevention of traffic anomalies.

There are no mobile and fully energy-independent means for detecting and preventing traffic jams, especially on works, roads and highways.

• à des systèmes « GPS »
• à des installations fixes, notamment à des réseaux de bornes,
• à des systèmes implantés à bord des véhicules eux-mêmes.

Known techniques, relating to the detection and signaling of stationary vehicles, or, more rarely, very slow down, call upon:

• to "GPS" systems
• fixed installations, in particular terminal networks,
• to systems installed on board the vehicles themselves.

• utilisation de caméras numériques, qui visionnent un secteur donné, et voient, de façon normale, des véhicules en mouvement. Dès qu'un véhicule est à l'arrêt, l'analyse des pixels au niveau de chaque caméra permet de déceler une anomalie et de signaler la présence d'un incident ;
• utilisation de radars Doppler. De façon similaire, dès qu'un radar constate l'immobilité d'un objet, quel qu'il soit, il y a anomalie.

The most advanced systems for automatic incident detection fall into two main categories:

• use of digital cameras, which view a given sector, and see, in a normal way, moving vehicles. As soon as a vehicle is stationary, the analysis of the pixels at the level of each camera makes it possible to detect an anomaly and to signal the presence of an incident;
• use of Doppler radars. In a similar way, as soon as a radar observes the immobility of an object, whatever it is, there is an anomaly.

However, such cap detection systems require a rather heavy fixed infrastructure, and are therefore expensive, and often limited to the outskirts of large cities and areas of heavy traffic on motorways, and designed for a programmed management.

There is a need for a mobile and autonomous means of energy, not relying on fixed installations, and not being connected to the network of origin equipping the channel concerned, in terms of energy supply and support of communication.

To be effective, such a system must be expert, autonomous in energy, and mobile.

Indeed, it is interesting to be able to dispose of it near mobile work sites, and in particular at the level of the channel restriction bezels.

Indeed, the presence of traffic jams on a construction site is classically considered as inevitable, and has not been the subject of studies to prevent them. However, such plugs prove to be accidentogenic, even at low speed, and an accident even of limited magnitude quickly creates, on a road network, a disturbance much higher than that created by the shipyard itself.

Such a system must be able to overcome, both users, a central control station, for an immediate reaction in case of traffic anomaly.

On the other hand, it must be able to communicate to these users and to this central control station instantaneous and reliable information on the state of traffic upstream of the site concerned, and regulation instructions, particularly speed.

• l'absence de communication filaire pour la fourniture d'énergie ou de supports d'informations ;
• la nécessité d'une implantation à proximité immédiate des voies de circulation ;
• le besoin d'un champ d'observation ou de vision important ;
• la nécessité de conjuguer, sur une certaine distance, de plusieurs centaines de mètres, des équipements capables de communiquer entre eux ;
• le support de moyens optiques très visibles par tout temps ;
• la nécessité d'une autonomie de fonctionnement de plusieurs jours ;
• la sensibilité aux conditions météorologiques ;
• le besoin absolu d'une maintenance minimale ;
• la protection contre le vandalisme.

Many constraints make it difficult to use mobile detection and prevention systems:

• the lack of wired communication for the supply of energy or information media;
• the need for an establishment in the immediate vicinity of the traffic lanes;
• the need for a field of observation or important vision;
• the need to combine, over a certain distance, several hundred meters, equipment capable of communicating with each other;
• the support of optical means very visible at all times;
• the need for an operating autonomy of several days;
• sensitivity to weather conditions;
• the absolute need for minimal maintenance;
• protection against vandalism.

The aim of the invention is to overcome the drawbacks of the state of the art by proposing a method of easy implementation, on areas not specially equipped, and free from the constraints of the environment. It offers a mobile device and autonomous energy implementation of this process, requiring no connection to a power supply network.

• on effectue un cantonnement de ladite voie en différentes zones, depuis l'aval vers l'amont d'un flux de circulation de véhicules sur ladite voie:
• une zone à capacité réduite;
• une première zone en amont, par rapport au sens du flux de circulation, de ladite zone à capacité réduite;
• au moins une second zone en amont de ladite première zone;
• on constitue, sur une période donnée, le spectre des vitesses des véhicules sur ladite voie dans chacune desdites zones à l'aide de moyens d'acquisition;
• on calcule en temps réel, à l'aide de moyens d'analyse auxquels on communique, par de premiers moyens de communication locaux lesdites vitesses, la vitesse moyenne dans chacune desdites zones ;
• on compare, à l'aide de moyens d'analyse, ladite vitesse moyenne à un premier seuil inférieur et à un second seuil supérieur dans ladite zone;
• on déclenche sur des moyens de signalisation une alarme d'état de congestion si une desdites vitesses moyennes dans une desdites zones est inférieure audit premier seuil inférieur de cette zone.

To this end, the invention relates to a method for detecting and preventing traffic jams on one or more traffic lanes at a site, characterized in that:

• the channel is subdivided into different zones from the downstream upstream of a traffic flow of vehicles on said road:
• an area with reduced capacity;
• a first zone upstream, with respect to the direction of the flow of circulation, of said zone with reduced capacity;
• at least one second zone upstream of said first zone;
• the spectrum of the speeds of the vehicles on said channel in each of said zones is constituted over a given period by means of acquisition means;
• in real time, by means of analysis means to which are communicated, by means of local first communication means said speeds, the average speed in each of said zones;
• comparing, with the aid of analysis means, said average speed at a first lower threshold and a second upper threshold in said zone;
• a congestion state alarm is triggered on signaling means if one of said average speeds in one of said zones is lower than said first lower threshold of this zone.

• des moyens d'acquisition, notamment sous la forme d'une caméra,
• des premiers moyens de communication, notamment sous la forme d'une liaison « Wifi »,
• des moyens autonomes d'alimentation en énergie et de stockage d'énergie,

et dont au moins l'un desdits moyens support mobiles comporte encore :

• des moyens d'analyse,
• des seconds moyens de communication, notamment par liaison radio, avec un poste de surveillance déporté,

et dont au moins l'un desdits moyens support mobiles comporte encore des moyens de signalisation.The invention also relates to a device for implementing said method, characterized in that it comprises at least two mobile support means for transporting and maintaining:

• acquisition means, in particular in the form of a camera,
• first means of communication, especially in the form of a "Wifi" link,
• autonomous means of supplying energy and storing energy,

and wherein at least one of said movable support means further comprises:

• means of analysis,
• second communication means, in particular by radio link, with a remote monitoring station,

and wherein at least one of said movable support means further comprises signaling means.

The invention therefore makes it possible to take charge of the management of traffic hazards over an area liable to experience disturbances.

The invention relates to the implementation of mobile equipment, which tracks the progress of work along a taxiway, adapting very quickly to the new position of a site.

• la figure 1 représente de façon schématisée et en perspective, une ou plusieurs voies de circulation cantonnée en zones selon l'invention;
• la figure 2 est un logigramme représentatif de la mise en oeuvre du procédé selon l'invention ;
• la figure 3 représente, de façon schématisée et en élévation, un moyen support mobile appartenant à un dispositif de mise en oeuvre du procédé selon l'invention.

Other characteristics and advantages of the invention will emerge from the following detailed description of non-limiting embodiments of the invention, with reference to the appended figures in which:

• the figure 1 shows schematically and in perspective, one or more zoned traffic routes according to the invention;
• the figure 2 is a flow diagram representative of the implementation of the method according to the invention;
• the figure 3 represents schematically and in elevation, a movable support means belonging to a device for implementing the method according to the invention.

The invention relates to the field of traffic management on road infrastructure, especially on motorways.

The invention relates more particularly to the detection of traffic jams on these road infrastructures. It is intended to perform, in real time, a traffic analysis to inform, on the one hand the users, and on the other hand a remote monitoring station.

A first embodiment of the invention is illustrated in the figures.

The use of the invention finds its application particularly on sites deliberately disturbed by technical necessities, especially in work areas, on any road section, especially in the open countryside, where there is no food resource in energy.

The invention is particularly applicable to real-time detection of plug formations, at the level of the channel restriction bevels, on construction site sites.

The method implemented by the invention is based on the analysis of the vehicle speed spectrum in different successive zones, on one or more traffic lanes, by acquisition means and analysis means coupled to means communicating with each other, and are designed to be mutually supportive. It is an expert tool, implemented by mobile and autonomous means of energy.

The method of detecting road plugs, according to the invention, makes it possible to monitor one or more traffic lanes 1 at a site 2.

• une zone à capacité réduite A. Cette zone A est notamment constituée par un chantier de travaux, une restriction de circulation suite à panne ou accident, ou autre ;
  • une première zone B en amont, par rapport au sens du flux de circulation, de cette zone à capacité réduite A;
  • au moins une seconde zone C en amont de la première zone B.

To implement it, a channel 1 is cantoned in different zones, from the downstream upstream of a traffic flow of vehicles on lane 1:

• an area with reduced capacity A. This zone A is notably constituted by a building site, a restriction of circulation following a breakdown or accident, or other;
  • a first zone B upstream, with respect to the flow direction, of this reduced capacity zone A;
  • at least a second zone C upstream of the first zone B.

The cantonment can of course be extended to other zones, if necessary, upstream of the second zone C.

The implementation of the process requires the treatment of data collected in these different areas.

First acquisition means 3 and traffic analysis 4 situated in the first zone B verify the fluidity of the traffic, in particular by measuring the speed of the vehicles, and by comparing it with adjustable thresholds, lower and upper.

Preferably, these acquisition means 3 and traffic analysis 4 are not intended to measure the speed of each vehicle, but to establish the speed spectrum of a vehicle flow flowing in a zone of cantonment during a certain observation period T.

Thus, over a given period T, the spectrum of the velocities V of the vehicles on the channel 1 in each of the zones A, B, C is obtained by means of acquisition means 3.

By means of local first communication means 5, the measured speeds, or the signals directly derived from the acquisition means 3, are communicated to analysis means 4.

In a preferred embodiment, the processing of the data by the analysis means 4 is a statistical processing, and the average speed VM is an aggregated average speed and the period T is equal to the duration of a treatment cycle carried out by the acquisition means 3, in particular an image processing cycle taken by a camera constituting these acquisition means 3. The acquisition means 3 may be of another nature, a Doppler radar for example.

We are therefore interested in the spectrum of the flux, and it is the induced slowdown of the flow by a stationary vehicle, which triggers the analysis of low or zero speed.

These means of acquisition 3 and analysis 4 of the traffic located in the first zone check the fluidity of the traffic, in particular evaluating the speed spectrum of the vehicles, and comparing a calculated average speed VM at adjustable thresholds, lower VB and higher VM. Below the lower threshold VB, for example 40 km / h, there is incident. Above the upper threshold VH, for example 60 km / h, the situation is considered normal. If the measured velocities of the vehicles are between the lower and upper thresholds, we are in a range of uncertainty.

The acquisition means 3 preferably consist of cameras or video, digital or analog detectors. The analysis means 4 are designed capable of performing a statistical processing of the data transmitted to them, after a possible decoding. The analysis means 4 are designed to constitute an expert system, with autonomous intelligence. They are especially designed to trigger alarms, including visual alarms, and to adapt the visual messages delivered to users according to the situation observed.

Each of the zones resulting from the cantonment, A, B, C, and any subsequent ones, may be equipped with such acquisition means 3 and analysis 4.

The first communication means 5 of each zone are designed to address and review information in relation to other communication means 5 connected to other acquisition means 3 and analysis 4 equipping other areas.

In particular, the means of acquisition 3 and analysis 4 of one of the zones contiguous to one of the zones where the average speed VM is in a range of uncertainty, have for mission to remove the possible uncertainty, and to confirm or refute the results recorded by the first means of acquisition and analysis.

If necessary, the information can be transmitted to a third zone, or to other zones.

The means of acquisition 3 and analysis 4 of each zone are also designed able to perform measurements and analyzes on the areas contiguous to theirs, if the relief terrain and infrastructure lends itself. These means thus make it possible to perform a mutual control of the zones, and to compensate for any material failures.

The acquisition means 3 and analysis 4 of each zone are also preferably designed able to perform measurements and analyzes in both directions of traffic, on tracks related, if necessary.

The communication technology of the first local communication means 5 is preferably an "Ethernet" network transmission system via "Wifi" or the like. The communication means 5 of each zone communicate with each other, and are still able to communicate in real time to or with a remote monitoring station 8 remote from the site 2, by means of second communication means 7. This last transmission is preferentially made by a link "EDGE3," GSM "at 128 kb, or similar.

In a preferred embodiment, if in one of the zones the spectral analysis calculates a mean speed VM, which is between said first lower threshold VB and the second upper threshold VH of said zone, then one is in a range of uncertainty. To remove the uncertainty, a new spectral analysis of the speed V is performed in the zone immediately upstream of the zone concerned. If this corroborates the slowdown, ie if the calculated average speed VM is lower than the lower threshold VB, or if it is also in the uncertainty range between the lower speed VB and the higher speed VM, a congestion state alarm is triggered.

It is still possible to carry out a new analysis, in the same area where there has been a slowdown or a transition to a range of uncertainty, using the acquisition means 3 of at least one of the areas adjacent to the concerned area.

With the aid of analysis means 4, the new spectral analysis of the average speed VM in the area concerned is calculated. And a congestion state alarm is triggered if this new average speed VM in this zone is lower than the first lower threshold VB of this zone.

The lower speed thresholds VB and higher VM can be parameterized for each zone. Preferably, they are the same for the related areas.

At least the area which is located furthest upstream in the traffic direction is equipped with signaling means 16, in particular in the form of variable message signs.

The invention advantageously makes it possible to improve responsiveness in the operational management of a plug, by providing real-time information to the users and the road network operator.

Thus, for the information of the users, the invention makes it possible to trigger, on signaling means 16, a congestion state alarm if one of the average speeds VM in one of the zones is lower than the first lower threshold VB of this zone. . Advantageously, the alarm is made visible to the users by signaling means 16, such as danger indicating signs, and / or speed limiting to a predetermined value, as the case may be, or calculated according to the average speeds VM calculated in each zone.

A cap alarm is triggered, in particular by the signaling means 16, if one of the analysis means 4 calculates a mean VM speed zero in any of the zones A, B, C.

Is transmitted preferably to a remote monitoring station 8, by means of second communication means 7, from at least one of the analysis means 4, the calculation results of average speeds VM, or / and signals from the means d acquisition 3, and in particular traffic images when these means 3 are cameras, or any information circulating on the first communication means 5. This remote monitoring station 8 can then trigger very upstream, up to several tens kilometers of the incident, speed limits, load shedding, law enforcement interventions, or giving instructions by radio or reporting the incident to transmitters in connection with receivers embedded by users, such as than mobile phones, "GPS" or others.

To implement this detection method, the invention also relates to means for implementing this method. These are constituted by mobile means, which are autonomous power supply and supply of the acquisition means 3, analysis 4 and communication 5, 7, and which include means for raising said acquisition means 3 and analysis 4.

According to the invention, a device 10 for implementing the method comprises at least two mobile support means 11, and preferably three or four.

In a preferred application, the equipment of each zone is made with such a mobile support means 11, such as a vehicle, preferably a trailer, which comprises acquisition means 3 and analysis 4, means for communication 5, energy supply means 12 and energy storage means 13, and, on at least the most upstream station, signaling means 16.

Each mobile means 11 is designed to be moved in a very short time, of the order of 4 hours, so as to leave one location, and join another, during the shift of a same technical team. For this purpose the means 11 is preferably a light trailer, single-axle, provided with rapid implementation stabilization means, and designed to be lifted, using at least one lifting point, by a means of lifting, to be arranged behind safety rails.

• des moyens d'acquisition 3, notamment sous la forme d'une caméra,
• des premiers moyens de communication 5, notamment sous la forme d'une liaison « Wifi »,
• des moyens d'alimentation en énergie 12 et des moyens de stockage d'énergie 13,

Each movable means 11 is designed capable of transporting and holding in working position:

• acquisition means 3, in particular in the form of a camera,
• first communication means 5, in particular in the form of a "Wifi" link,
• energy supply means 12 and energy storage means 13,

• des moyens d'analyse 4,
• des seconds moyens de communication 7, notamment par liaison radio, avec un poste de surveillance déporté (8).

At least one of the mobile support means 11 combined to constitute the device 10 further comprises:

• analysis means 4,
• second communication means 7, in particular by radio link, with a remote monitoring station (8).

Preferably, the transmissions, in particular between mobile means 11, are made using multidirectional antennas, so as to avoid pointing from one to the other, and reduce the time of implementation on the site 2 ..

At least one of said mobile support means 11, preferably one intended to be situated furthest upstream in the direction of the traffic, further comprises signaling means 16. This particular means 11 remains individually usable for any other use, which ensures its optimal use.

Preferably, each of the mobile support means 11 comprises analysis means 4, and second communication means 7. This redundancy makes it possible to mitigate possible failures, or still advantageously allows an intensification of the calculations by modifying the reference period T.

Each of the acquisition means 3 is designed to measure the speed of vehicles in at least two distinct and related traffic areas. It is further conceived capable of transmitting by means of first communication means 5 quantification signals of the measured instantaneous speeds.

It is still conceivable to entrust these means of acquisition 3 the monitoring of two directions of traffic, on related tracks. However, preferably, the acquisition means 3 are doubled, so as to affect each of them to monitor a single direction of movement. The mobile support means 11 concerned then receives a set of acquisition means 3 and additional analysis 4, for additional monitoring of the other direction of movement, without burdening the analysis and treatment protocols.

Thus, road traffic can be monitored and analyzed by rear-view, either by a dome-type camera with two front and rear objectives, or by two cameras, one of which is rear-facing.

The first communication means 5 of any one of the mobile support means 11 are designed capable of transmitting to the analysis means 4 of any of the mobile support means 11 signals. These signals may come from any of the acquisition means 3 of the device 10 relating to a traffic zone, for their statistical processing and the eventual triggering of a congestion or plug warning signal.

In sum, the device 10 according to the invention comprises, in the preferred embodiment, mobile support means 11 polyvalent elements.

The device 10 according to the invention overcomes, in part, the problems of relief. Classically good results are obtained with a set of at least three movable means 11, preferably four, at least the one located furthest upstream in the direction of traffic is equipped with signaling means 16. Such a configuration can, in particular , allow surveillance of one or more lanes for approximately 2 kilometers, if not more. The implementation of each mobile support means 11 is made at the option of the operator, depending on the available shoulders, and barriers constituted by safety barriers, buildings, escape routes, and the relief of the site.

In this regard, it is necessary to take into account the slope and sinuosity of the site, for good optical monitoring by the acquisition means 3, as well as for transmissions of information in the best conditions by the first 5 and second 7 means of communication. In order to be free from the annoyance caused by turns, ramps, structures such as bridges spanning the track, acquisition means 3 and analysis 4 are advantageously placed in height relative to the ground , at a relative altitude of several meters, especially greater than 8 meters.

For this purpose, and as visible on the figure 3 , at least one of the movable support means 11, and preferably each of them, comprises elevation means 14 for raising above the channel 1 at least the acquisition means 3, and preferably all the acquisition means 3 and analysis 4, and the first 5 and the second communication means 7. This characteristic makes it possible for each of the mobile means 11 to overcome the relief and the structures, and to monitor a relatively large area of several hundred meters in length.

These elevation means 14 are of the telescopic type or the like. The elevation means 14 are designed to allow rapid deployment during implementation, such as a quick reset in road position. They are designed to put the expensive equipment that is the means of acquisition 3 and analysis 4 out of reach of vandalism. It should be noted, in this connection, that these latter devices can provide their own security by self-monitoring, and / or by monitoring the neighboring mobile means 11 within the same device 10.

For a layout along the track, far from any infrastructure, the mobile means 11 are energy independent, and comprise energy supply means 12, and energy storage means 13.

The energy supply means 12 are autonomous and preferably consist of sets of photovoltaic cells. This energy autonomy is, again, a safety factor, insofar as no agent is necessary to make power supply connections, roadside section and weathering.

Autonomy of more than six days is desirable in territories like France, or other fog-sensitive areas, where the weather and sunshine are not always optimal to ensure a sufficient supply or recharge. Statistically it is considered that the value of six days corresponds to a lapse of time allowing the recharging of the storage means. The energy storage means 13 are therefore designed able to conserve and deliver the energy necessary for the operation of the mobile means 11 for a minimum of six days. In the preferred case where the energy storage means 13 are constituted by batteries, the capacity of the latter is preferably calculated to deliver, for six days, the energy corresponding to the maximum consumption.

Preferably, a mobile means 11 has a capacity greater than 1000 Ampere / hour. However, this does not concern the trailer or trailers equipped with signaling means 16 by variable message panels, the higher energy consumption of which requires additional energy storage means, which are preferentially dedicated to it, and which are calculated for the same duration, preferably more than 800 Ampere / hour. It is still possible to implement additional energy generation means, especially in the form of a self-starting generator set.

Also we choose more particularly devices with low energy consumption. In particular, the acquisition means 3 are preferably ultra-low power day / night IP cameras with a power of 3W.

In regions such as France, the autonomy of six days statistically guarantees the possibility of continuous recharging of the energy storage means 13. It is thus possible to use the mobile means 11 for a very long time, for example one year, between two periodic maintenance operations such as the verification of batteries, the cleaning of cells constituting the energy supply means 12, or the cleaning and periodic maintenance of the acquisition means 3 and analysis 4, communication means 5 and 7, and elevation means 14.

Photovoltaic cells are preferably the energy supply means 12. They are arranged in panels of small width, so as to be easily registered in the template of light vehicles or small trailers, constituting the mobile means 11. Their extension is preferentially done in the direction of the height. A preferred embodiment, as visible on the figure 3 , consists of the juxtaposition of panels articulated on axes parallel to each other, allowing them to fold over each other in the manner of a wallet. Preferably, these cells are four panels in 12V, coupled in 24V.

For a better yield, south orientation of the cells is preferable, in the absence of a bulky and heavy tracking system. For this purpose, the set of photo-voltaic cells 12 is fixed on a mast or support, preferably rotatable about a vertical axis, in particular under the action of maneuvering means such as a crank and a conical torque . This mobility makes it possible to have the folded panels in the optimal transport configuration, and contributes to the speed of implementation or setting in road configuration of the mobile transport means 11. A variant can consist of the use of solar collectors 12 provided with repositioning means designed to ensure optimum performance. The energy supply means 12 may also be constituted by one or more wind turbines, or comprise, in particular in addition to photo-voltaic cells or the like.

Preferably, the mobile means 11 comprises at least one charge controller for managing and optimizing the energy production and utilization data.

Service constraints, such as the low possibilities of implantation of the mobile means 11 on the site 2 near the traffic lanes 1, necessarily lead to limiting the volume, and if possible the weight, to allow their positioning on the shoulders little stabilized. These site constraints restrict the possible locations, hence the particular interest of elevation means 14, which make it possible to overcome the other constraints of the site.

Thus, preferably, the mobile means 11 comprise rolling means for their rapid transposition on another site, and are constituted by trailers of mass less than 1000 kg, towable by light vehicles such as vans or 4x4 vehicles. These mobile means 11 can still receive ancillary services, such as lighting for construction crews, or the like.

• moyens d'acquisition 3, tels que caméras ;
• moyens d'analyse 4 et de détection automatique de bouchons
• premiers moyens de communication 5 locaux avec d'autres moyens mobiles, en particulier « Wifi » ;
• seconds moyens de communication 7 avec un poste de surveillance déporté 8, qui peut être très éloigné, de plusieurs dizaines ou centaines de kilomètres, en particulier « EDGE/GPRS » ;
• moyens de génération d'énergie 12;
• moyens de stockage d'énergie 13;
• moyens d'élévation 14;
• moyens de signalisation 16, en particulier sous forme de panneaux à messages variables.

It will be understood that each of the moving means 11 is designed so that it can, depending on its positioning on the site 2, on one or the other of the different zones A, B, C, comprise all or part of the equipment mounted on its support means:

• acquisition means 3, such as cameras;
• analysis means 4 and automatic detection of plugs
• first means of communication 5 local with other mobile means, in particular "Wifi";
• second communication means 7 with a remote monitoring station 8, which can be very far, of several tens or hundreds of kilometers, in particular "EDGE / GPRS";
• energy generating means 12;
• energy storage means 13;
• elevation means 14;
• signaling means 16, in particular in the form of variable message panels.

In sum, it is understood that the configuration of these mobile means 11 allows total independence of terrestrial infrastructures.

The communication between the mobile means 11 is facilitated by protocols for transmitting observations made on the movements of the vehicles in the different zones, and protocols for managing these observations, which ensure the possibility of mutual surveillance of the zones A, B, C by the various mobile means 11. Each movable means 11 can take over a mobile means 11 upstream or downstream fault, and monitor the traffic both upstream and downstream of the flow of vehicles.

The quantification of the physical quantities measured, here essentially speeds, by a statistical estimation of averaging, brings a great advantage over the prior art all-or-nothing. Indeed, the observation and the confirmation of decelerations in the different zones A, B, C, makes it possible to detect any slowing down, and to prevent a stopper, by giving sufficiently in time, upstream, speed reduction instructions, in particular by means of variable message panels 16, where it is thus possible to display the most appropriate recommended speed for the smooth flow of the flow.

Preferably, a delay triggers the extinction of the messages intended for the users, in particular on the variable message panels 16, after the end of a disturbance, and the observation of a predetermined period without particular slowdown detection, for example of a few minutes.

The versatility of the devices 10 and moving means 11 according to the invention allows their use in detecting plugs, as well as for preventing plugs and informing users.

The invention offers the great advantage of minimizing maintenance, and avoiding any human intervention on the site, which is particularly important when one knows the high level of the risk of accident for a pedestrian on a highway, and what is more on a delicate zone of intervention as a zone of works.

Claims (15)

1. Method for detecting traffic jams on one or several roads (1) at the level of a site (2), wherein :

   - a signal line block of said road (1) is performed in different areas, from downstream to upstream of a vehicle traffic flow on said road (1) :

   - a reduced-capacity area (A) ;

   - a first area (B), upstream with respect to the direction of the traffic flow, of said reduced-capacity area (A) ;

   - at least a second area (C) upstream of said first area (B) ;

   - over a given period (T) is formed the spectrum of the speeds (V) of the vehicles on said road (1) in each of said areas (A, B, C) through acquisition means (3) ;

   - the average speed (VM) in each of said areas is calculated in real time through analysis means (4) to which said speeds (V) are transmitted through first local communication means (5) ;

   - said average speed (VM) is compared, through analysis means (4), to a first lower threshold (VB) and to a second upper threshold (VH) in said area;

   - a congestion-state alarm is triggered on signaling means (16) if one of said average speeds (VM) in one of said areas is lower than the first lower threshold (VB) of this area.
2. Method according to claim 1, wherein, if in one of said areas said average speed (VM) is between said first lower threshold (VB) and the second upper threshold (VH) of said area, a new calculation of the speed (VM) is performed in the area upstream of the area involved, and a congestion-state alarm is triggered if the average speed (VM) in said upstream area is lower than said first lower threshold (VB) of this area, or if it is within the range of uncertainty between the lower speed (VB) and the supper speed (VM).
3. Method according to claim 1, wherein, if in one of said areas said average speeds (VM) is between said first lower threshold (VB) and the second upper threshold (VH) of said area, a new measurement of the speed (V) is performed in said area involved, through the acquisition means (3) of at least one of the areas adjacent to said area involved, which measurement is transmitted, through first communication means (5), to analysis means (4) that calculate the new average speed (VM) in said area involved, and a congestion-state alarm is triggered if said new average speed (VM) in said area is lower than said first lower threshold (VB) of this area, or also if it is within the range of uncertainty between the lower speed (VB) and the supper speed (VM).
4. Method according to one of the preceding claims, wherein a traffic-jam alarm is triggered if one of said analysis means (4) calculates a zero average speed (VM).
5. Method according to one of the preceding claims, wherein said average speed (VM) is an aggregate average speed and said period (T) is equal to the duration of a processing cycle of an image taken by a camera forming said acquisition means (3).
6. Method according to one of the preceding claims, wherein the results of the calculation of said average speeds (VM) or/and the signals proceeding from said acquisition means (3) are transmitted from at least one of said analysis means (4) to a remote monitoring station (8) by second communication means (7).
7. Mobile device (10) for implementing the method according to any of the preceding claims, wherein it includes at least two mobile supporting means (11) designed capable of transporting and holding:

   - acquisition means (3), namely in the form of a camera,

   - first communication means (5), namely in the form of a « Wifi » connection

   - autonomous energy-supply (12) and energy-storage means (13), and of which at least one of said mobile supporting means (11) also includes:

   - analysis means (4),

   - second means for communicating (7), namely by radio connection, with a remote monitoring station (8),

   and of which at least one of said mobile supporting means (11) also includes signaling means (16).
8. Mobile device (10) according to claim 7, wherein each of said acquisition means (3) is designed capable of measuring the speed of vehicles in at least two different traffic areas connected to each other and of transmitting through said first communication means (5) signals for quantizing the measured instantaneous speeds.
9. Mobile device (10) according to claim 7 or 8, wherein said first communication means (5) of any of said mobile supporting means (11) are designed capable of transmitting to the analysis means (4) of any of said mobile supporting means (11) signals proceeding from any of said acquisition means (3) of said device (10) related to a traffic area, for their statistical processing and eventually triggering an alarm signal.
10. Mobile device (10) according to one of claims 7 to 9, wherein at least one of said mobile supporting means (11) includes hoisting means (14) designed capable of hoisting above said road (1) at least said acquisition means (3).
11. Mobile device (10) according to claim 10, wherein said hoisting means (14) are designed capable of hoisting said acquisition means (3) at an altitude of more than 8 meters with respect to the ground.
12. Mobile device according to one of claims 7 to 11, wherein it includes energy-storage means (13) designed capable of holding and delivering the energy necessary for its operation for a minimum period of six days, and supplied with energy by autonomous energy-supplying means (12).
13. Mobile device (10) according to claim 12, wherein said energy-storage means (13) are batteries with a capacity of at least 1000 Amperes/per hour.
14. Mobile device according to one of claims 7 to 13, wherein each of said mobile means (11) includes acquisition means (3), first communication means (5), autonomous energy-supplying (12) and energy-storage means (13), analysis means (4), second communication means (7), and hoisting means (14).
15. Mobile device (10) according to one of claims 7 to 14, wherein said mobile supporting means (11) include rolling means for quick transposition, and at least one hoisting point designed capable of permitting their handling by means of a hoisting apparatus.

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