GB2050769A - Road traffic signalling arrangement - Google Patents

Abstract

There is described an arrangement for providing information to motorists along a road wherein road markings S1, S2 e.g. centre lines, include passive responders which cooperate with a secondary radar arrangement R carried by the vehicle V to provide coded information. The output of the responders may be modified by e.g. the presence of ice on the road. <IMAGE>

Description

SPECIFICATION Composite device for positive operation of road signaletics and method for making use thereof The present invention concerns a device which in its entirety is formed by the cooperative combination of a plurality of active and respectively passive electronic components, that jointly are fitted for positively providing electromagnetic informations, and of horizontal signaletic components, fitted for positively providing optical informations. The present invention concerns also a method for carrying out and taking advantage, in the field of road signaletics, of said cooperative combination of devices.

It is known that because of the evermore increase of traffic and of the trend to raise the average speed of the vehicles, the problems concerned with the road signaletics, which is carried into effect by providing complete informations from the road to the vehicles' drivers, are evermore heavier and it is believed that systematically structurate such informations should be absolutely necessary, for improving the completeness and the reliability of the data which are to be supplied to said vehicles' drivers for example for timely warning them about approaching dangerous crossings and/or potentially dangerous road sections and so on.

Such problems are well far of being solved, notwithstanding the plurality of proposals and of attempts made. According to some widely considered proposals, this problem is at the present time faced by anticipating the installing of active transmitter components, located at about the critical section of the thorough-fare road and designed for supplying to receiving components aboard of the vehicles the required data or informations. This mode of solving the above problems is complicate and extremely costly either because of the number of the active components which are necessary to cover and protect the critical spots and situations, and because of the necessarily uninterrupted operation, feeding and control thereof. It is evident that the absence or/and a missing or defective reception of a critical signal could lead to seriousest crashes.

On the other hand it is acknowledged that the current road signaletics, either the vertical one and the well more efficient horizontal signaletics, are well far from providing a proper manner for solving the above considered problem. The present signaletics, or road signalization system, except the substantially uncommon occurrence of mostly intervehicular acoustical signalings, is exclusively grounded upon the sight detection of the signals and upon the fact that a constant attention must be paid to the direction of travel.This sight detection is affected by the visibility conditions which are at their turn influenced by seasonal and weather factors, and therefore to provide the vehicles with means suitable for receiving, decoding and signaling to the driver (and/or to the vehicle instruments) signaletics data, is at the present time assumed to be the essential condition in view of the safety of the vehicle traffic.

According to the invention, there is herein proposed to associate active transmitting components aboard of the vehicle, the so called "secondary radars", with passive components, particularly dipoles, which are suitably and selectively located beneath a road marking layer consisting of a prefabricated tape, or beneath or within the underlayer (or primer layer) on which the marking is formed, the said dipoles being designed and arranged for receiving energy from the secondary radar aboard of the approaching vehicle and returning it thus providing the requested elektromagnetic information, while the signaling material provides the requested optical information.

It is known that said secondary dipoles, usually termed "responders", can consist of simplest resonance circuits formed in their simplest actuation of thin metal plates which are suitably dimensioned relatively to the wave length of the energy which is applied to the secondary radar.

It has been ascertained that the well known prefabricated tape material in use for horizontal road signaling, jointly with the related carrying or sticking primer Lnderlayers laid down with said marking forming tape or strip, forms a most adapted support for these responder dipoles. Such stripes or tapes, prefabricated together with the related suitably oriented and spaced secondary dipoles, after having been laid down and arranged for service on the road, maintain their horizontal signaling action unaffected and provide with the related dipoles arranged beneath the actual signaling layer, a corresponding plurality of passive responder means and as such they do not require any own energy for feeding the resonance circuit. The importance and the advantages of the invention are evident.The information which is received by the active receiving component aboard of the vehicle exciusively depends from the existence and availabiiity of the responder dipole, which gets into resonance simply when energy from the approaching secondary radar is received.

The number of the informations, additionally to the return beam modulation, can be increased by means of complementary resonance elements consisting also of small metal plates. The arrangement of secondary dipoles to be met along the travel can be suitably coded and decoded by a computer associated to the transmitting and receiving active unit or assembly, for selectively and unmistakably providing the required positive information.

It is well known the recent development of radar equipments with the purpose of preventing crashes in thick fog. It is evident the advantage of transforming such equipments for the multiple use according to this invention.

Informations of interest such as about weather conditions can be provided also. For example the existence of ice into a recess preliminarily formed in the capacitive circuit of the dipole noticeably modifies the response parameters, providing thus a very valuable information (the existence of ice on the road).

Several further complemental informations can be had by associating to the system, in particular to the active component a source of infrared rays which can be returned and suitably modulated to and respectively by the passive components. In the U.S. Patent No.4,129,397 granted to the present applicant there has been disclosed a road marking strip comprising reflex reflector elements which can easily be modified and adapted for infrared energy reflection. It is known that by taking advantage of such suitably modulated energy a great number of informations can be had.

Additionally, and in consideration of the promptness and simplicity with which the signalling stripes or tapes can be provisionally also laid down and located over road pavements, the system according to the invention, further to insuring the continuous provision of locally preprogrammed informations, can also provide a transient service for example for warning the vehicle drivers about road interruptions or other events and occurrences.

These and other more specific features of the invention will be made apparent from the following detailed description of some examplificative embodiments of same invention, said description being referred to the accompanying drawing wherein, with some diagrammaticalities and simplifications: Fig. 1 illustrates a roadway portion A comprising a marking strip provided with a series of dipoles each forming an individual resonance circuit; Fig. 2 fragmentarily illustrates the strip S provided with a dipole D consisting of a thin pressworked out aluminum plate; Fig. 3 fragmentarily illustrates a modified embodiment of the dipole, provided with a variable oscillating circuit DB, and Fig. 4 diagrammatically and fragmentarily illustrates an embodiment of supplemental coding.

Referring now particularly to the drawings: as diagrammatically illustrated in Fig. 1, a vehicle V is provided with a known secondary radar R so arranged that it comprises a dipole antenna secured below the same vehicle, the vehicle being prepared to travel along the roadway A following the path defined and indicated by the horizontal signaling. The active component R is suitably computerized for decoding the informations provided by the waves reemitted by the dipoles (examples of which are illustrated in Figs. 2 and 3) existing in the signaling strip S (only one strip is illustrated, for simplicity sake, along the roadway A). This signaling strip can be either uninterrupted or at spaced sections, such as indicated at S2 and respectively at S 1 for providing by itself the information that overtaking is prohibited and respectively admitted.The corresponding information (an uninterrupted series of spaced signals and respectively short spaced series of signals) is provided to the vehicle by the computerized active component R.

What above provides an example of basic coding. Fig. 4 provides an example of supplemental coding, in which differing series of signals and as for example a uniform sequence C provides a response related to the vehicle speed, while differing groupings G1, G2 and G3 have suitably coded meanings. The resonance circuit consisting of the dipoles ream its the energy in the form of a plurality cf harmonics, the third one of which is preferably taken advantage of, because that third harmonics is the strongest one.

In view of giving to the antenna of the resonance circuit a dimension in proper relationship with the strip which embodies within its layers the metal sheet dipoles, rather high frequencies are obviously made use of.

For example, the transmitting-receiving assembly, that is the secondary radar which on the vehicle embodies the active component of the system, makes preferably use, in transmission, of microwaves between 0.6 and 1.2 GHz.

Practically, for the best results, the transmitting antenna and the resonance dipole are arranged transversally to the signaling line. This fact sets up a limitation of the lowest frequency (a straight dipole 25 cm long corresponds to a frequency of 600 MHz.). Such limitation does not exist for the high frequencies, besides of the higher costs, the greater sensitivity to humidity and the increase of the loss coefficients of the materials, but practically the frequencies which will be selected for the anticrash radar equipments will establish the frequencies of the equipments under discussion.Just as an example, with a transmitter having a frequency of 1 GHz and an output of 0,5 watt, at a distance of 5 m from the signaling strip, it has been obtained, at a speed of 20 km/h of the vehicle and by dry road surface, a response on the third harmonic of 1,4 microvolt, while in the occurrence of wet road surface the response has been of 1,55 microvolt.

Obviously the new composite device has been described and illustrated limitedly to its essential components, and as in indicative but not limiting example only. The passive dipoles, generally indicated at D in Figs. 2 and 3 can well have a differing geometry and complication, provided that they can form a resonance circuit responsive to the signal emitted by the secondary radar R.

Similarly, the characteristics of the secondary radar could be modified, provided that high frequencies would be made use of.

Correspondingly, the manner of locating the passive dipoles can be modified, such dipoles being arranged below the prefabricated signaling or marking layer, possibly as a tape or ribbon fitted in the sticking carrying underlayer (primer) of the strip.

The laying down of such prefabricated strip having, below the properly signaling layer, the reflecting or resonant passive elements, confers to said strip the double ability of visually identifiable horizontal signaletics, and of providing electromagnetic informations by means of elements which are selectively in resonance with the secondary radar of the vehicle. For the above reasons there must be understood that within the scope of the patent herein applied for any equivalent inventive concept will be encompassed as inferred by what hereinabove disclosed and more particularly as defined in and by one or more.

of the following.

Claims (16)

1. Composite device for positive operation of road signaletics, characterized by the cooperative combination of transmitting and receiving active electronic components, typically secondary radars aboard of the vehicle and designed for emitting energy in the direction of travel along the road, of passive components which are selectively located beneath a prefabricated tape-like layer, and designed for returning said energy to the receiving components on board of the vehicles, providing positively informations, and of signaling horizontal components, for positively providing optical informations to the motorist.

2. Composite device for positive operation of technics of information in the field of signaletics, during vehicle travel along roadways, provided with horizontal signaling means embodied by prefabricated signaling stripes located on and secured to the road pavement, characterized by the fact that the passive components are directly associated to the tape-like road signaling material.

3. Composite device as to claims 1 and/or 2, characterized by the fact that the said passive components consist of dipoles so designed, oriented and dimensioned that the energy is returned to the said receiving components placed on the vehicle.

4. Composite device as to one or more of claims 1 to 3, characterized by the fact that the said components operate in the range of radar frequencies.

5. Composite device as to claim 4, characterized by comprising passive components which return harmonics of the signal.

6. Composite device as to one or more of claims 1 to 5, characterized by the fact that the said active components consist of secondary radars the antennas of which are directional and are arranged below the related vehicles for irradiating energy in form of microwaves aiming to the responder passive components arranged along the roadway in the said direction.

7. Composite device as to one or more of claims 1 to 6, characterized by the fact that the receiving component comprises a computer for decoding and taking advantage of the informations provided by the microwaves which are reemitted by the passive responder components existing on the road.

8. Composite device as to one or more of claims 1 to 7, characterized by the fact that the passive responder components are provided with an oscillating variable resonance circuit.

9. Method for making use of composite devices as to one or more of claims 1 to 8, characterized by taking contemporarily advantage of dipoles forming passive components, located below a road signaling layer, for selectively sending signals produced by vehicle borne secondary radars for providing such vehicles with electromagnetic informations in the field of signaletics, and of a signaling horizontal layer for providing to said vehicles optical informations.

10. Method as to claim 9, making use of passive dipoles which structurally belong to road signaling stripes in service on the roadway, characterized by taking advantage of return signals form said dipoles, which signals are consistent with the meaning of the signaling visualized by the horizontal signaletics actually in service.

11. Method as to one or more of claims 9 and 10, characterized by taking advantage of the information returned by the passive responder components for getting informations about the status of the road surface.

12. Method as to claim 11, characterized by taking advantage of an actual icy status into a recess associated to the capacitive circuit of the dipoles for obtaining informations about the status of the road surface, in particular about the presence or the absence of ice on the said surface.

13. Method as to one or more of claims 9 to 12, characterized by using a computer decoding the return signals got by the passive dipoles in view of obtaining informations in the field of signaletics.

14. Method as to one or more of claims 9 to 13, characterized by taking advantage of ancillary informations provided by the modulated return of infrared energy by part of reflectors which are selectively arranged on the road and are impinged by radiations emitted by a vehicle borne optical source, for getting informations complemental of those got by selective return of radar microwaves.

1 5. Composite device for positive operation of road signaletics substantially as described herein with reference to the accompanying drawings.

16. Method for making use of composite devices substantially as described herein.