EP0675472A1 - Device for the detection of data of passing vehicles on a road - Google Patents

Abstract

The sensor (100) is placed in a groove (120) formed in the top surface of a road (111). A first section of the sensor (20) has a U-shaped cross-section and is placed in the groove. A piezoelectric, coaxial cable (10) is inserted in the narrow channel defined by the first section. A second section (30) is fitted into the top of the U-shaped channel above the piezoelectric cable. The second section fills the remaining space above the cable to leave a flat top surface. <IMAGE>

Description

The invention relates to a device for detecting data relating to the passage of vehicles on a roadway, to be placed in a groove formed in the upper part of this roadway, comprising a first profile provided with an upper U-shaped recess, and a piezoelectric cable of the coaxial type disposed in the bottom of the recess of the first profile.

The invention finds its application in the detection of passage of vehicles, counting, measurement of speeds, measurement of the masses of vehicles (dynamic loads) and their classification and this in all regions having diverse climatic conditions and in particular severe (climate very hot, temperate or very cold).

Patent FR 2 482 340 describes a device for detecting passage on a roadway, its laying method and its application to speed detection.

This device is partly made up of a piezoelectric effect cable. This cable is a coaxial shielded cable whose core and sheath are separated by a piezoelectric ceramic. This cable has an outside diameter of a few mm, and a length of the order of 1 m or more. It is therefore very thin and long.

In order to increase the service life of the piezoelectric cable, to facilitate its installation in the roadway, and to ensure a certain reliability of the measurements, this piezoelectric cable is placed at the bottom of a rigid metal or hard plastic profile, having either the shape of a U, or the shape of a rectangular quadrilateral whose upper face is curved. This profile is internally filled with a plastic material curable by polymerization. The aim is to provide a rigid device.

In a variant of this device, the profile rigid is coated on its three faces not intended to be in contact with vehicles, with an overmolded envelope of flexible plastic, for example a resin loaded with elastomer, to absorb vibrations. This arrangement is carried out in the factory.

In either case, the method of installing the device includes forming a groove in the pavement, of dimensions slightly larger than those of the device. Then the bottom and the sides of the groove are coated with a flexible plastic absorbing vibrations, and finally the device is placed in the coated groove, so as to fix it, while making it protrude slightly from the upper surface of the pavement. If the profile has the shape of a U, the upper parts of the branches of the U protrude from the upper level of the road by a few mm. The coating of the groove is not essential when the device already comprises a molded envelope of flexible plastic produced in the factory.

A disadvantage of the aforementioned device known from the prior art is that its manufacture uses plastics, which are organic materials and which are particularly sensitive to temperature variations.

An object of the invention is the detection of the speed of vehicles, but also, in addition to counting, the detection of the masses of moving vehicles (measurement of dynamic loads) and their classification. The detection and analysis of this data is particularly important for the forecast of new roads, new bridges, or pavements of all kinds, as well as for the forecasts concerning their maintenance.

If organic materials are used to make the detection devices, the measurements are not reliable as regards the detection of the masses of the vehicles, since these measurements depend on the climatic conditions. Depending on the case, these measures may be non repetitive, even impossible in regions where the climatic conditions are severe.

In addition, in the case where it is necessary to also use a plastic material to fix the device in the roadway, difficulties or impossibilities appear in regions where the climatic conditions are severe (scorching heat, extreme cold, very high humidity , great climatic differences between the seasons, or between days and nights, etc ...).

Another drawback of the known device is that the polymerizable plastic material for filling the U-shaped profile is brittle, does not age well, and is easily detached from the walls of this hard protective profile. This means that the device obtained does not support any bending. In its first variant, this device is therefore generally fragile, especially for use on a deformed or curved road; and in particular it is ill-suited to the measurement of moving loads.

In its second variant of implementation, it is still not flexible, and it is always fragile due to the use of plastics, but it is better suited to the measurement of masses in motion due to its overmolded envelope. However in this case, it becomes difficult and costly to carry out; indeed, the realization of an overmolding supposes the realization of a mold, which must be changed each time that a person skilled in the art wishes to modify the lengths or the transverse dimensions of the devices: or the devices must have different lengths according to the uses for which they are intended: measurements on roads, on highways, measurements relating to a half-width of axle, or to a total width of axle, use of piezoelectric cables of different diameters etc ... A mold further deteriorates with l 'use.
Finally, demolding is difficult because of the fragility of the thermosetting resin for filling the profile.

It is also known from the state of the art, by patent application EP 0 231 669, a device for detecting data relating to the passage of vehicles, to be inserted in a groove formed in a pavement, which also comprises a piezoelectric cable , protected by a hard U-shaped profile, and embedded in a filling material for the profile. In this second cited document, the profile has a substantially square section, and is made of metal, for example aluminum; the cable is at a given distance from the bottom of the profile; the filling material to drown the cable is an epoxy mortar loaded with silica. The sides of the U-profile are provided with elastomeric foam to absorb longitudinal bending. The assembly is introduced into a groove made in the pavement and is again embedded in an epoxy mortar loaded with silica.

This second device cited has two advantages over the first device cited, which are: an improvement in performance in the measurement of masses in motion, since it is correctly sensitive to vertical pressures; and an improvement in weather resistance because the filling material in epoxy mortar loaded with silica is essentially provided for this purpose. However, it has notable drawbacks: the first drawback was already present in the first device mentioned, and lies in the fact that this second device is also not flexible because the filling resins loaded with silica are very brittle; the second drawback is that it is even more expensive to implement than the second variant of the first device, because its structure is very complex; moreover, the positioning of the piezoelectric cable at a given distance from the bottom of the profile is difficult to achieve, since it is not easy to keep the thin and long cable at a well-determined distance during this filling.

An object of the present invention is to provide a device for detecting data relating to the passage of vehicles on a roadway, capable of performing as well in simple measurements as counting vehicles, or measuring speeds, as in measuring masses in motion.

Another object of the invention is to provide such a device capable of providing the different types of measurement over a wide range of temperatures.

Another object of the invention is to provide such a device in particular capable of mechanically withstanding both bad weather and the repeated passage of heavy vehicles.

Another object of the invention is to provide such a device which is flexible and can be installed on the upper surface of roadways, possibly subject to deformation over time, for example under the effect of bad weather such as swelling due to rain. , frost, crackles, cracks etc.

Another object of the invention is to provide such a device which is very simple to produce and very inexpensive, and which is also simple to install in the roadway; so that, for the installation, the circulation is interrupted only for an extremely short period of time.

These objects are achieved by means of the detection device defined in the preamble, further characterized in that it comprises a second profile disposed in the recess of the first profile above the coaxial cable, this second profile having a shape and dimensions such that it fills and fills the remaining volume of the recess above the cable, and that it realizes the closing of this recess.

• il est performant dans une large gamme de températures,
• il peut être utilisé pour tout genre de mesures relatives à la détection de masses dynamiques ou autres données relatives aux véhicules,
• les pressions exercées par les véhicules ou par les masses dynamiques sont correctement transmises, c'est-à-dire qu'il est correctement sensible aux pressions verticales.
• il montre peu de dispersions des caractéristiques de mesure,
• il est très résistant aux intempéries et aux facteurs de dégradation mécanique,
• il est suffisamment flexible pour être installé en tout lieu,
• il est constitué de matériaux peu sensibles au vieillissement et non friables à la flexion,
• il est extrêmement simple et rapide à réaliser et son coût de fabrication est faible, alors que ses performances sont extrêmement bonnes,
• il est facile à mettre en place dans une chaussée : le temps nécessaire à son installation est faible et les moyens à mettre en oeuvre sont peu coûteux ;
• et en outre il est facile à transporter avant la pose.
  L'invention est décrite ci-après en détail en référence avec les figures annexées dont :
• la FIG.1A représente en coupe transversale un dispositif comprenant deux profilés et incluant un câble coaxial piézoélectrique, et la FIG.1B représente ce dispositif en coupe longitudinale ;
• la FIG.2 représente en coupe transversale un câble coaxial piézoélectrique ;
• les FIG.3A et 3B représentent respectivement en perspective chacun des profilés utilisés dans le mode de réalisation illustré par les FIG.1A et 1B ;
• la FIG.4 représente en coupe transversale un dispositif selon les FIG.1A et 1B, installé dans une chaussée.

The device according to the invention has several advantages in particular:

• it performs well in a wide range of temperatures,
• it can be used for all kinds of measurements relating to the detection of dynamic masses or other data relating to vehicles,
• the pressures exerted by the vehicles or by the dynamic masses are correctly transmitted, that is to say that it is correctly sensitive to vertical pressures.
• it shows little dispersion of the measurement characteristics,
• it is very resistant to weathering and mechanical degradation factors,
• it is flexible enough to be installed anywhere,
• it is made of materials not very sensitive to aging and not brittle in bending,
• it is extremely simple and quick to produce and its manufacturing cost is low, while its performance is extremely good,
• it is easy to install in a roadway: the time required for its installation is low and the means to be used are inexpensive;
• and in addition it is easy to transport before installation.
  The invention is described below in detail with reference to the appended figures, of which:
• FIG.1A shows in cross section a device comprising two sections and including a piezoelectric coaxial cable, and FIG.1B shows this device in longitudinal section;
• FIG.2 shows in cross section a piezoelectric coaxial cable;
• FIG.3A and 3B respectively represent in perspective each of the profiles used in the embodiment illustrated by FIG.1A and 1B;
• FIG.4 shows in cross section a device according to FIG.1A and 1B, installed in a roadway.

• un câble piézoélectrique coaxial 10, de diamètre externe d₁ faible, par exemple quelques mm. Le câble coaxial piéozoélectrique 10 peut avoir une longueur D allant de quelques dizaines de cm à plusieurs m ;
• un premier profilé 20, comme en outre représenté en perspective sur la FIG.3B, muni d'un évidement 21 en forme de U, à sa partie supérieure 22 ; cet évidement 21 a une dimension transversale ℓ₁ de valeur suffisante pour recevoir le câble piézoélectrique 10, c'est-à-dire que cette dimension ℓ₁ est légèrement supérieure au diamètre d₁ ; cet évidement 21 a en outre une profondeur ℓ₂ par rapport à la face supérieure 22 du profilé qui est telle que lorque le câble piézoélectrique 10 est disposé dans le fond 23 de l'évidement 21, il est à une distance appropriée Δ de la surface de la chaussée, une fois le dispositif 100 installé dans une rainure pratiquée dans cette chaussée. Ce premier profilé 20 a une longueur L légèrement supérieure à celle du câble coaxial 10 et l'évidement 21 est pratiqué sur toute cette longueur L ; ce premier profilé 20 a en outre des dimensions transversales externes, hauteur et largeur ℓ₃, ℓ₄ grandes vis-à-vis de celles de l'évidement 21 ; c'est à dire que la largeur ℓ₄ est environ 5 à 10 fois la largeur ℓ₁ ; et la hauteur ℓ₃ environ 2 ou 3 fois la profondeur ℓ₂.
• un second profilé 30, comme représenté en outre en perspective sur la FIG.3A, de dimension transversale ℓ'₁ juste inférieure à la dimension transversale ℓ₁ de l'évidement 21 du premier profilé 20, pour être introduit dans cet évidement, une fois le câble coaxial 10 déjà installé au fond 23 de cet évidement ; et de hauteur ℓ'₂ capable d'emplir, de combler et de fermer le volume restant libre de l'évidement 21 du premier profilé, lorsque ce second profilé 30 est placé au-dessus du câble coaxial 10 dans l'évidement 21. Ce second profilé 30 a une longueur L' identique à la longueur L du premier profilé 20 et de l'évidement 21.

As shown in FIG. 1A, in cross section, and 1B in longitudinal section, the device 100 for detecting data relating to the load measurements dynamic or passing vehicles on a roadway includes, to be later arranged in a groove on the surface of the roadway:

• a coaxial piezoelectric cable 10, of small external diameter, for example a few mm. The piezoelectric coaxial cable 10 can have a length D ranging from a few tens of cm to several m;
• a first profile 20, as further shown in perspective in FIG.3B, provided with a U-shaped recess 21 at its upper part 22; this recess 21 has a transverse dimension ℓ₁ of sufficient value to receive the piezoelectric cable 10, that is to say that this dimension ℓ₁ is slightly greater than the diameter d₁; this recess 21 also has a depth ℓ₂ relative to the upper face 22 of the profile which is such that when the piezoelectric cable 10 is disposed in the bottom 23 of the recess 21, it is at an appropriate distance Δ from the surface of the roadway, once the device 100 installed in a groove made in this roadway. This first profile 20 has a length L slightly greater than that of the coaxial cable 10 and the recess 21 is made over this entire length L; this first profile 20 also has external transverse dimensions, height and width ℓ₃, ℓ₄ large vis-à-vis those of the recess 21; that is, the width ℓ₄ is about 5 to 10 times the width ℓ₁; and the height ℓ₃ about 2 or 3 times the depth ℓ₂.
• a second profile 30, as also shown in perspective in FIG. 3A, of transverse dimension ℓ'₁ just less than the transverse dimension ℓ₁ of the recess 21 of the first profile 20, to be introduced into this recess, once the coaxial cable 10 already installed at the bottom 23 of this recess; and of height ℓ ₂ capable of filling, filling and closing the remaining free volume of the recess 21 of the first profile, when this second profile 30 is placed above the coaxial cable 10 in the recess 21. This second profile 30 has a length L 'identical to the length L of the first profile 20 and of the recess 21.

• le câble coaxial piézoélectrique a un diamètre externe d₁, de l'ordre de 3 mm. Le diamètre d₁ peut être choisi autre, selon la sensiblité de détection désirée, sachant que la sensibilité d'un câble piézoélectrique augmente proportionnellement à son diamètre ;
• ce câble piézoélectrique a en outre une longueur totale D qui peut être soit 2 m pour les mesures relatives au passage d'un demi-essieu (1 roue), soit 3.10 m pour les mesures relatives au passage d'un essieu complet (2 roues montées transversalement) ;
• le premier profilé 20 à des dimensions externes ℓ₃, ℓ₄ qui sont toutes deux égales à environ 20 mm. Dans ce premier profilé, la profondeur de l'évidement ℓ₂ est de l'ordre de 10 mm et sa dimension transversale ℓ₁ juste supérieure au diamètre d₁ du câble est alors de l'ordre de 3,2 mm ;
• le second profilé 30 a une dimension transversale ℓ'₁ juste inférieure à la dimension ℓ₁ transversale de l'évidement 21, c'est-à-dire environ 3 mm, et sa hauteur ℓ'₂ pour emplir, combler et fermer l'évidement 21 quand le câble 10 est en place au fond 23 de cet évidement, est de l'ordre de 8,5 mm.

In a preferred embodiment:

• the piezoelectric coaxial cable has an external diameter d₁, of the order of 3 mm. The diameter d₁ can be chosen other, according to the sensibility of detection desired, knowing that the sensitivity of a piezoelectric cable increases in proportion to its diameter;
• this piezoelectric cable also has a total length D which can be either 2 m for measurements relating to the passage of a half-axle (1 wheel), or 3.10 m for measurements relating to the passage of a complete axle (2 wheels mounted transversely);
• the first profile 20 has external dimensions ℓ₃, ℓ₄ which are both equal to about 20 mm. In this first profile, the depth of the recess ℓ₂ is of the order of 10 mm and its transverse dimension ℓ₁ just greater than the diameter d₁ of the cable is then of the order of 3.2 mm;
• the second profile 30 has a transverse dimension ℓ'₁ just less than the transverse dimension ℓ₁ of the recess 21, that is to say approximately 3 mm, and its height ℓ'₂ for filling, filling and closing the recess 21 when the cable 10 is in place at the bottom 23 of this recess, is of the order of 8.5 mm.

In this preferred embodiment, the total length L and L 'of the two sections 20 and 30 is 3.20 m ± 1 cm, and the other general tolerances are ± 0.1 mm.

To obtain the desired performance of the device for measuring dynamic loads, detecting passage or measuring vehicle speed, with the required temperature resistance and resistance to mechanical degradation, the two sections 20 and 30 are made of a material selected.

According to the invention, the material is preferably formed from a reinforcement of threads or fiber fabrics of glass, which is first impregnated with resin (polyester or epoxyphenolic), and which is then drawn inside a die, and further heated to allow the polymerization of the impregnation resin.

• ces profilés montrent une haute résistance mécanique,
• les formes de ces profilés peuvent être réalisées à la demande, dans des usines ou fabriques spécialisées dans la fourniture d'articles en fibre de verre laminé. Comme ces articles sont fabriqués industriellement, et en moyennes ou grandes séries, ils sont bon marché ; et les performances sont répétitives (Ex. : Société PULTRUSION, Z.I de NOGEL, 60870 Villers-St-Paul, FRANCE)
• ces profilés propagent correctement les pressions verticales pour permettre au câble piézoélectrique d'effectuer les détections et mesures requises ;
• ces profilés sont à la fois suffisamment rigides et suffisamment flexibles pour permettre le transport aisé des dispositifs avant leur installation, et la mise en place des dispositifs dans toutes sortes de situations défavorables ;

   Selon l'invention, le montage des trois pièces 10, 20, 30 les unes vis-à-vis des autres est très facile :

• 1) le premier profilé 20 est présenté,
• 2) le câble 10 est posé dans le fond de l'évidement 21,
• 3) une colle 40 est répandue sur le câble, légèrement en excès ; la colle peut être par exemple une résine époxy telle que AW116 CIBA CEIGY,
• 4) le second profilé est posé en surface du câble dans l'évidement, de manière à ce que la colle s'infiltre et remonte entre le premier et le second profilé, le long des faces verticales de l'évidement en U,
• 5) la colle est polymérisée.

These profiles then have many advantages:

• these profiles show high mechanical strength,
• the shapes of these profiles can be produced on demand, in factories or factories specializing in the supply of laminated fiberglass articles. As these articles are manufactured industrially, and in medium or large series, they are inexpensive; and the performances are repetitive (Ex .: PULTRUSION company, ZI de NOGEL, 60870 Villers-St-Paul, FRANCE)
• these sections correctly propagate the vertical pressures to allow the piezoelectric cable to carry out the required detections and measurements;
• these profiles are both sufficiently rigid and sufficiently flexible to allow easy transport of the devices before their installation, and the installation of the devices in all kinds of unfavorable situations;

According to the invention, the assembly of the three parts 10, 20, 30 one against the other is very easy:

• 1) the first profile 20 is presented,
• 2) the cable 10 is placed in the bottom of the recess 21,
• 3) an adhesive 40 is spread on the cable, slightly in excess; the adhesive may for example be an epoxy resin such as AW116 CIBA CEIGY,
• 4) the second profile is placed on the surface of the cable in the recess, so that the glue infiltrates and rises between the first and the second profile, along the vertical faces of the U-shaped recess,
• 5) the glue is polymerized.

According to the invention the epoxy resin is used in small quantity, only to hold the parts together, and it does not constitute a material for transmitting pressures: therefore it does not constitute a surface which works - contrary to what occurred in particular the first document cited as a state of technique-. In the device produced according to the invention, there are therefore no drawbacks which were inherent in the use of epoxy resin in the devices known from this state of the art.

In the device according to the invention, the first means for protecting the piezoelectric cable -which were a hard U-shaped structure in the first state of the art-, and the second means for drowning the cable -which were the filling with the only resin epoxy in this state of the art- are combined and produced overall by the coating formed of the first and second profile, the resin playing for this reason a secondary role limited to the bonding of the parts.

In addition, as the profiles are made of fiberglass impregnated with resin, the resin added for bonding is perfectly suited to this material and plays its role correctly: it adheres perfectly to the walls of the profiles and does not risk coming apart, as c was the case of the resin filling the aluminum profiles for example, in the prior art in question.

Thus the device obtained according to the invention can be slightly curved without deterioration; it ages well, its longevity is improved, and it retains its performance under all weather conditions.

• une sensibilité de : 0,78 V./Bar,
• une homogénéité de : ± 6.8 %.

A titre de comparaison, les normes édictées par le ministère français du transport sont :

• homogénéité, pour mesure des charges dynamiques : ± 7 %
• homogénéité, pour comptage des véhicules : ± 20 %

In tests, the device 100 according to the invention has shown:

• a sensitivity of: 0.78 V./Bar,
• homogeneity of: ± 6.8%.

For comparison, the standards issued by the French Ministry of Transport are:

• homogeneity, for measurement of dynamic loads: ± 7%
• homogeneity, for vehicle counting: ± 20%

• une âme métallique 11, habituellement en cuivre, de diamètre d₂ environ 1 mm,
• une gaine métallique 12, habituellement en cuivre, de diamètre externe d₁ environ 3 mm,
• une poudre piézoélectrique compactée 13 de remplissage entre l'âme métallique 11 et la gaine métallique 12 par exemple la poudre "PXE5", de fabrication PHILIPS. Un câble piézoélectrique particulièrement approprié à la mise en oeuvre de l'invention est le câble VIBRACOAX, référence "30 P1C" de la Société THERMOCOAX (Suresnes -FRANCE).

With reference to FIG. 2 which represents a coaxial piezoelectric cable 10, in cross section, the latter comprises:

• a metallic core 11, usually made of copper, with a diameter of around 1 mm,
• a metal sheath 12, usually made of copper, with an external diameter of around 3 mm,
• a compacted piezoelectric powder 13 for filling between the metal core 11 and the metal sheath 12, for example the powder "PXE5", manufactured by PHILIPS. A piezoelectric cable which is particularly suitable for implementing the invention is the VIBRACOAX cable, reference "30 P1C" from the company THERMOCOAX (Suresnes -FRANCE).

As shown in FIG.1B, the coaxial piezoelectric cable 10 is connected, by a connector 15, to a coaxial transmission cable 16. Preferably, a reference cable "RG 58 will be used in conjunction with the piezoelectric cable VIBRACOAX Cu "from the company THERMOCOAX. Given the diameter of the coaxial cable used, the connection between this coaxial cable 10 and the transmission extension cable 16 is always fragile; to overcome this drawback, it suffices to coat the connector 15 and a small length of the extension in the system consisting of the first and second sections 20,30, and to stick using glue 40 according to the method of the invention.

The operation of a piezoelectric cable for pressure detection is well known to those skilled in the art: when the piezoelectric material is subjected to an external pressure - here, in the cable 10, the piezoelectric material is subjected to a radial pressure - it delivers electrical charges which are collected by the central conductor 11, or metallic core, of the cable 10. The metallic sheath 12 is brought to ground.

To obtain this effect, the compacted piezoelectric powder undergoes a radial polarization treatment during the manufacture of the cable, and therefore shows a sensitivity of the order of 1 V / Bar.

With reference to FIG. 4, once the device 100 according to the invention has been completed, a trench 120 or groove is made transverse to the upper surface 111 of a roadway 110, in the region where the measurements are required; when the device 100 according to the invention has external dimensions ℓ₃, ℓ₄ of the order of 20 mm, the trench 120 is made of slightly larger dimensions by means of a mechanical device, suitable for cutting road surfaces. Then the device 100 is installed in this trench 120. Maintaining the device 100 in the trench 120 is simple.

The device 100 is suspended at the correct height relative to the upper surface of the roadway and is glued with a material which depends on the roadway material. It can be an epoxy resin loaded with sand which is well suited to a concrete pavement or methylmetacrylate which is better suited to asphalt. Other adhesives can be used depending on the type of asphalt or the type of special coating.

Thus arranged, the device 100 is subjected, during the passage of the wheels of vehicles traveling on the roadway, to pressures to which it responds by the emission of electrical signals.

The device 100 is connected by means of the transmission cable 116 to suitable measuring devices, and not shown because they are not strictly part of the invention, which process the electrical signals transmitted, and provide the required data relating to the dynamic masses, on detection of passage, and / or vehicle speed, etc.

Claims (9)

Device for detecting data relating to the passage of vehicles on a roadway, to be placed in a groove made in the upper part of this roadway, comprising a first profile 20 provided with an upper recess (21) in the shape of a U, and a piezoelectric cable (10) of the coaxial type disposed in the bottom (23) of the recess (21) of the first profile (20),
characterized in that it comprises a second profile (30) disposed in the recess (21) of the first profile (20) above the coaxial cable (10), this second profile (30) having a shape and dimensions such that it fills and fills the remaining volume of the recess (21) above the cable (10), and that it realizes the closing of this recess (21). Device according to claim 1, characterized in that the material constituting the profiles (20,30) is a glass fiber impregnated with polymerized resin, and in that to form the closure of the recess (21) whose bottom (23 ) is provided with the cable (10), the second profile (30) is secured to the first profile (20), by means of an adhesive (40). Device according to claim 2, characterized in that the adhesive is a polymerizable resin. Device according to one of claims 1 to 3, characterized in that the piezoelectric cable is of the type comprising a metallic core, a metallic shield and a piezoelectric ceramic material arranged in a dense manner between the core and the shield. Device according to claim 4, characterized in that the piezoelectric cable (10) is electrically connected to a coaxial connection cable (16) by a coaxial connector (15), connection cable intended to be connected by its other end to devices recording and data processing of the piezoelectric cable, and in that the connector (15) and the adjacent end of the connection cable (16) is enclosed between the two profiles (20, 30), the latter having a length, as well as a recess length greater than that of the piezoelectric cable. Device according to claim 5, characterized in that, for the detection of data relating to the passage of vehicles in a roadway, the first profile (20), provided with the connected coaxial cable, and provided with the second profile (30) glued (40) , is placed in the groove (120) at the upper part of the roadway (110), so that the upper part (22) of the branches of the U of the first profile (20), and the upper part of the second profile (30) is flush with the upper surface (111) of this roadway. Device according to one of Claims 1 to 6, characterized in that the length of the piezoelectric cable and of the profiles is between 20 cm and 5 m, and in that the diameter of the piezoelectric cable is of the order of 3 mm, the transverse dimension (ℓ₁) of the recess (21) of the first profile is slightly greater, by a few tenths of a mm to the diameter of the cable, and the transverse dimension (ℓ'₁) of the second profile to ensure the closing of the recess (21) is of the order of the diameter d₁ of the piezoelectric cable. Device according to one of claims 1 to 7, characterized in that the external transverse dimension (ℓ₄) of the first profile is 5 to 10 times that (ℓ₁) of the recess (21), and the height of this profile is approximately 2 to 3 times that (ℓ₂) of the recess. Device according to claim 8, characterized in that the depth of the recess is of the order of 10 mm.

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