Electronic traffic control system

Advanced system for electronic control of traffic in real time and for bi-directional code and clear transmission between an operating center and vehicles along a road section

These are known systems for traffic control and in particular for the detection of accidents along a road section.

These systems are based on the use of induction coils 5 placed under the road, transverse to the axis of the road, in alignments separated from each other by a few hundred meters, systems by which a possible accident or any another abnormal situation concerning the free use of the road is indicated in a central station by the detection of a line of vehicles occupying the last alignment crossed by the vehicle accident before its halt.

In such systems, the response time required to detect an accident is a function, at the same time, of the distance between the alignments of induction coils, the number of vehicles involved in an accident, the speed and the traffic intensity.

If the distance between successive alignments decreases, it is clear that the response time also decreases; however, the number of detection alignments increases for the same road section and, therefore, the cost of installation, without obtaining, however, continuous and immediate control of traffic conditions.

On the other hand, since the turns must be buried under the roadway transversely to the axis of the road, such control systems have a certain rigidity in the sense that possible modifications to the installations, when the traffic conditions are no longer the same, require not only expensive work but above all the interruption of traffic for the entire period necessary for the installation or removal of facilities relating to the road.

For the same reason, that is to say because of the fact that systems based on the use of induction coils must be placed under the road, transverse to the axis of -la. road, claim high handling costs. Indeed, the ruts, the movements of the ground, the repair of the pavement of the roadway and even the ordinary handling of the latter, cause the stretching of the conductors consti30 killing the whorl, which leads to frequent repairs of the whorls themselves.

Such drawbacks do not exist in equally well-known systems, based on the use of doppler radars. Such devices require, however, installation on a pole, which results in an extension of the detection area and, consequently, less discrimination in controlling the number of vehicles and other traffic parameters. On the other hand, the use of Doppler radars is much more expensive than that of induction coils even if it results in a certain reduction in the barriers without determining a significant increase in the response time.

Experience has shown that these known systems do not give satisfactory results, especially with regard to the fundamental requirement of ensuring rapid intervention at the right time.

The present invention consists of an improved system for electronic control, in real time, of the flow of vehicles on a road section, in particular on a motorway section, capable of producing in a simple, practical and economical manner:

- Ιθ- continuous detection of traffic parameters for each section in which the road section is divided and, at the same time, observation of weather conditions in at least one section of this same section;

- electronic development of the speed, density, flow and traffic distribution characteristics with the forecast of the evolution of the speed and density parameters over time (for each section) and in space (the along the controlled route), depending on the morphological characteristics of the road (profile, extent and layout) and local weather conditions;

- the calculation of the differences of the parameters observed compared to those predicted and the triggering of alarm devices, when the differences go beyond threshold values. -4 fixed, through the automatic triggering and the control of optical signals at ground, such as semaphores, variable and similar traffic signs, and / or by means of transmission to vehicles on the section, and provided with a receiving device or a receiving / transmitting apparatus, of messages in code for the activation of on-board optico-acoustic signals, and / or for the transmission in clear to the vehicles of pre-recorded and coded standard messages , transmitted automatically, or from my 10 particular wise persons on intervention of the operating center and / or the control center;

- transmission from vehicles to the operating center, code messages for vehicle identification, request for help, etc.

- two-way clear communication between vehicles and the operating center and / or control center;

the transmission, from the ground, in correspondence of determined points, of messages in code for the execution of elementary instructions, for example the request for a course, by means of manual pressure on a button;

- memorizing the data supplied and the operations carried out, detecting damage and failures of the main components of the whole system and of each accessory system.

The improved system, object of the present invention, is thus capable of achieving effective traffic control, carried out in real time, by increasing the degree of safety and the efficiency of the highways equipped with such a system.

'In terms of safety, the system allows the rapid identification of accidents and / or other extraordinary danger conditions, such as, for example, those depending on adverse weather conditions (poor visibility, rain, snow, ice formation,') wind speed etc.) offering the user, in due time, optical and / or acoustic warning information and the possibility of requesting assistance, in clear or in code, without getting out of the vehicle,

The increase in the degree of efficiency is achieved, on the other hand, by 'interventions carried out, preferably, by • the control center in order to regulate' the flow of traffic along the motorway, each time the density traffic is approaching the saturation point and traffic is tending to become chaotic due to disruption caused by users or other unforeseen situations.

The same system, as has already been said, allows the continuous link, in plain language, between a central station, for example the operating center, and the vehicles traveling the road section equipped and equipped with radio-receiver apparatus. This link is not only usable for communications concerning the indication of abnormal traffic conditions or the organization of emergency services in case of need, but also for the transmission or retransmission of any program which is broadcast. , such as music, disclosure, advertising or other programs, with total elimination of parasites and fading zones due to the location of the transmitting station (s) or repeaters as well as to the surrounding orographic and meteorological conditions, including sections in tunnels.

The connection is also made in the opposite direction, that is to say from the vehicles to the central, with the same behavioral characteristics, even in the most unfavorable topographic and meteorological conditions.

Other characteristics and advantages of the invention will appear in the following description and in the drawings

V attached where is represented, to. indicative but not limiting, a preferred embodiment of the invention.

Figure i - This is a hloc diagram of the perfection • 5 system born for electronic control, in real time, of the flow of vehicles along the road section provided for this purpose, according to the present invention.

Figure 2 - This is a diagram of the installations along a road section, according to the present invention.

Figure 3 - This is a diagram of the installations which depend on a post in the diagram in Figure 2.

Figure 4 - This is the diagram of a traffic data transmission device. '

Figure 5 - This is the diagram of a traffic data receiving device.

The block diagram in FIG. 1 shows a double system of detectors 3a and 3b placed along the section to be checked.

They are able to continuously collect information concerning the transit of vehicles 1 respectively the weather conditions 2 which they transmit to a control computer 4. Each detection station 3a and 3b is interrogated by the control computer 4 at intervals such that, according to the theory of sampling, they allow the reconstruction of the functions represented by the development of the parameters measured over time, for each section, and in space, along the stretch.

This control computer 4 collects and decodes all the signals received, is responsible for a first examination of the data making it possible to recognize the flow conditions. traffic and, on the basis of the instructions received by the computer of the control center 7, evaluates the forecasts of the traffic in each section of road, records the differences which exceed the threshold values ​​fixed by the program of the computer 7, sets in motion an alarm device by automatically operating, by means of a command and control system 5a, the optical signals on the ground

8 (semaphores and / or variable message signs) placed at strategic points of the section by transmitting to the operational center 6 and to the central computer 7 a specific message.

In the same cases of exceeding the threshold values, jointly or alternatively with the triggering of the optical signals on the ground, the control computer 4, thanks to the system 5b, automatically transmits to vehicles in transit or having stopped along the road placed under control, messages in code on a determined frequency, for the activation of the optico-acoustic signals of the devices possibly provided 15 aboard the vehicles J, transmitting, at the same time, information both at the operation center 6 and at the central computer 7.

This computer 7 records in the mass memory 7a the messages concerning the detected events and, when this is planned by the program, predisposes the transmission in clear on the section concerned, through the system 5.0, âe. standard pre-recorded and coded warning messages.

On the other hand, from the command console of the center, operative 6 it is possible, upon operator intervention, to transmit to users, specific messages in code or in plain text not provided by the central computer 7 and / or to operate the signals 8 manually and / or thus transmit or retransmit, on the frequency fixed by the system, the programs on air, such as, for example, musical programs, of dissemination, advertising and other programs with the elimination of parasites and / or fading areas.

Two channels are provided with alternative modulation on the same carrier f ^; one of the two channels, indifferently, jatgaMataMM · * η

is reserved for the transmission, or retransmission of the programs while the other channel is intended for the transmission of traffic messages, the switching between the two channels being controlled automatically by the control center 7, through the computer 4, on the general program schedule, or manually, at the request of the operating center 6.

The link between the vehicles 1 and the control center 7 is bidirectional, either in code, through the system 5b, or in plain text through the system 5c ,.

. In practice, there is no obstacle to transmitting in code in both directions to all users in order to make it possible to send simple messages, identify the vehicle, request emergency assistance, etc. The clear link, on the other hand, is advantageously ex. 15 tensible to all in the only direction going from the center towards the users, while in the direction of the vehicles towards the center it must be reserved for reasons of expediency, only service and / or authorized vehicles.

On the other hand, in relation to the stations located at the edge of the road where the systems 5a, 5b, 5c converge, of each elementary section 2 which forms the subdivisions of the network implementing the control system, object of the present invention, a device 9 has been provided with manual control, for example a button which uses · part of the clear channel and thus consents the transmission of messages in code for carrying out elementary instructions such as, for example, the request for help in the direction of the operational center 6.

Finally, it is expected that all the instructions executed automatically and / or manually and all the results of the observations are recorded by 6a 'and 7b reqoectiveinent with the operational center 6 and the control center 7 in order to ensure management control and to build up archives of all events for statistical, administrative and legal purposes. Under £ 7 is indicated the control console of the control panel lSC5LTJTJff! LWiTTT—— mentioned above, thanks to which intervention on the system is possible, independently of the general program prefixed.

The control of the parameters of interest takes place through a plurality of detection barriers distributed along the road at predetermined intervals and capable of providing indications on the presence of vehicles, the time of permanence in the controlled area their enumeration , their size and speed.

. As has been said and as shown in FIG. 2, the control system, object of the present invention, is divided into elementary sections 11, of variable length, preferably but not exclusively from two to eight kilometers, comprising a certain number detection and control barriers

12 connected to a station 10, represented, for example, by a cabinet with the installations for the realization of systems

5a, 5b, 5c and the detection of the meteorological conditions as well as the manual control device 9. The location of the station should preferably be located approximately in the middle of the elementary section 11. The stations 10 correspond to a certain number of elementary sections 11, preferably but not exclusively from four to six stations 10 for each lesson 11, are connected by channels based on telephone-type lines 13 to a control computer 4 , in turn connected to the operating center 6 and to the control center 7. The operating center 6 and the control center 7 are also interconnected.

In principle, for the detection of traffic parameters, conventional detectors such as doppler radars and induction coils could be used; However, in order to reduce the difficulties and the cost of the installation of the devices and their handling, a new radio frequency detector has been designed, capable of providing a signal of an order of magnitude proportional to the mass of the vehicle observed and d '' a duration proportional to that of occupation of the controlled area.

Such a detector is essentially constituted by a transmission device 14 operating on a wavelength, prefixed preferably comparable to the physical dimensions of the vehicle (three-four meters) and by a reception device 15.

The transmitter 14 and the receiver 15 can be placed on the same side of the road, using the reflected wave as a useful signal, or opposite one another on both sides of the road, using as the useful signal Attenuation of the direct wave. Although the first solution is a less costly installation, the second seems safer because the installation is much less sensitive to disturbances due to polluting radio frequencies and false reflections.

Such arrangements of the transmitter 14 and the receiver 15 relating to a single-carriageway road. In the case of two-lane roads, such as motorways in general, the detection system comprises a single transmission device 14, placed between the safety rails for the separation of traffic, and a pair of receivers 15 placed on both edges of the road. Experience has shown that the ideal distance between two successive detection devices 12, constituted by the transmission 14 and reception 15 devices in pairs or triplicate, is one hundred to two hundred meters and depends, in any case, on the altimetric and planimetric characteristics of the route as well as average parameters of the speed and density of traffic, observed statistically during the project phase.

As can be seen in FIG. 4, the transmission device 14 is essentially constituted by a sinusoidal generator 16 remotely powered and by a radiant element 17 biased by a door circuit 18 according to a synchronism 19 prefixed and adjusted by the control computer 4, while the receiver 15, as seen in FIG. 5, is constituted by an antenna 20, 'by a magnitude detector 21 and by a high gain amplifier 22, remotely powered and connected to a coupler 23 for the transmission of the useful signal.

w "£ * <5g * 32jj3SH" i

B

The transmission apparatuses 14 and the reception apparatuses 15 are connected respectively to cables 24 and 25.

The cable 24 is used for the transmission of the synchronism signal and for the remote supply of the installations, while the cable 25 is used for the transmission of the detected signal and, as the above, for the remote supply of the installations. The cables 24 and 25 are of the two-wire type, but it is preferable that the cable 25 which connects the receivers 15 is of the coaxial type, taking into account the structure of the signal to be transmitted.

The length of the cables 24 and 25 corresponds to the length of one of the elementary sections 2 in which the control system is subdivided.

The detection of the traffic parameters is carried out by transmitting, through the transmitter 14, pulse trains of a fixed duration, adjusted by a synchronism signal produced by the control computer 4. The receiver 15, harmonized on the frequency of the transmitter 14, picks up these signals, detects the level and amplifies it. Such a level is at its maximum when the area controlled is in rest condition (absence of vehicles in transit or stopped) while any disturbing event causes an attenuation of the received signal or a reinforcement of the reflected wave proportional to the physical dimensions of the disruptive vehicle.

The synchronism signal produced by the control computer 4 is received, in correspondence with the station 10 of each elementary section, of the channel A, supported by a line of. telephone type 13, and sent to the transmission devices 14 and to the reception devices 15 of each dam 12 by means of a signal extraction coupler 26 and a second coupler 27 intended to superimpose the signal itself on the supply voltage, the circuit of which is not shown in the drawing. ·.

- 12 Activation of each transmitter · 14 and acquisition from the receiver 15 of the given signal are carried out in parallel, the activation frequency being "such that it allows identification by sampling of the phenomenon observed (passage of each vehicle), the signals coming from the dams 12 of each elementary section II are composed in series in a single message which is sent to the control computer 4 through a link coupler 28 using the channel C of the line 13.

The data provided by 4 are observed in such a way that one can estimate the state of occupation of each section of the highway and the difference in the forecast value based on the measurements made in the previous section; provide forecast parameters for the next road section and identify abnormal situations by triggering the signals 8 in the cases provided and transmitting the results to the operational center 6 and to the control center 7. Each station 10 also comprises a coupler 29 for command and control of the optical signals 8 and, when this is provided, a recording coupler 30 for the detection of the data transmitted by the meteorological detector or detectors 3a of the traditional type.

The coupler 29 and the coupler 30 are connected with the channel A indicated above, the first to receive the activation signal and to transmit the control signal, the second to transmit the data collected. Parallel to the cables 25 of each elementary section 11, there is provided a radiant system essentially constituted by a transmission line balanced on two conductors 32 and 33, ter30 'mined on its own characteristic impedance Z „, so that the magnetic field thus product is homogeneous and independent of any obstacles or screens that may exist between the two carriageways, for example the wall separating the two arches of a tunnel.

Where the stations 10 of each section are located, the two conductors 32 and 33 are connected by a positive disassembly device 34 to a reception / transmission installation, the transmitting part of which essentially comprises a sinusoidal lift generator 35 controlled in frequency and in phase by synchronism signals transmitted via channel A of line 13 and a large modulator

36 with its own power amplifier 37, guided by the low frequency signal derived from channel A or channel B of line 13 by a switch 38, thus allowing the discrimination of the areas interested in transmission.

The switch 38 between the two channels A and B at low frequency is controlled by the control computer 4 but if necessary it is possible to intervene on the base channel directly from the control console of the operating center 6.

The receiving part of the reception and transmission installation of each station 10 is, in turn, essentially made up of a modulator-demodulator 39, or modem, which is responsible for transferring on channel B of line 3a 13 the information captured by the system mentioned above and the code instructions received by the manual control device 9 which is connected to it.

The transmission in the clear is preferably of the induction type in order to limit the zone of influence to only the zones surrounding the motorway, taking into account the smallness of the power transmitted while the uncoupler 34, provided for so as to use the same radiant system for transmission and reception, both in code and in clear, contains the filters concerning the frequencies f ^ and f₂ used by the two functions and ensures the galvanic separation between the installations and the

- 14 radiant system.

It seems appropriate to note that the four channels A, B, C, and D can consist of four bi-couples of a telephone cable or produced by transmission in multiplex, that is to say on carrier frequencies. conducted by the same support, for example a coaxial cable of known type or a high frequency bicouple, the communications in clear on the channels A, B, and D go directly to the operating center 6, while the messages in code of channel C and those of channel D pass through the control computer 4 and from the latter go to the control center 7. the sectioning in the elementary sections 11 of the line which constitutes the support of the channels C and D being carried out physically or by means of radio-frequency filters.

The reception of transmissions, according to the system which is the subject of the present invention, is carried out on board vehicles by the use of installations of known type which can be tuned to the frequency f ^, unique for the entire network.

For example, for the reception of clear transmissions, a radio receiver with ferrite antenna and fixed tuning on said frequency f j. For service vehicles, on the other hand, provision is made for the use of installations, also known, capable of producing a bi-directional link in semiduplex using the same radiant system on different frequencies, for example: for reception and fg for transmission.

These facilities allow the connection between the vehicles and the operating center, and vice versa, both in tunnels and in all other gray areas not served by the radio bridge.

The following link between the operating center and the terminal station of the section served by the radiant system, according to the present invention, can be achieved, indifferently, by using a low frequency line, for example a telephone line. , or a radio bridge, depending on local availability.