Process for conditioning and for placing a traffic sensor

• US 5,520,056 A
• Filed: 06/01/1994
• Issued: 05/28/1996
• Est. Priority Date: 04/01/1993
• Status: Expired due to Fees

• Current Assignee: Etat Francais Represente Par Le Ministere De L'Equipment, Du Logement Des Transports Et De L'Espace, Centre D'Etudes Techniques De L'Equipment
• Original Assignee: Etat Francais
• Inventors: Buisson, Claude, Fillastre, Daniel, Violette, Erice
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US08/252,470
• Time in Patent Office: 727 Days
• Field of Search: 73/786, 73/866.5, 73/DIG. 4, 73/784, 310/338, 310/340, 310/345, 310/348, 340/933
• US Class Current: 73/784
• CPC Class Codes: E01F 11/00 Road engineering aspects of Embedding pads or other sensitive devices in paving or other road surfaces , e.g. traffic detectors, vehicle-operated pressure-sensitive actuators, devices for monitoring atmospheric or road conditionspressure-sensitive elements G01L; traffic control systems G08G
• CPC Class Codes: G08G 1/02 using treadles built into the road pads or other sensitive devices responsive to passage of vehicles E01F11/00

Abstract

Process for packaging a sensor (1) to be placed in a road (2), characterized in that it consists in covering said sensor (1) with threads (8) of organic or inorganic material extending over the entire length of sensor (1) and in burying the whole in a binder that hardens by polymerization, so as to obtain a bar (7) containing said sensor (1).

Claims

1. A process for conditioning a traffic sensor comprising at least one step of encapsulating said sensor in a strengthening organic mass comprising threads of organic or inorganic material, said threads consisting essentially of substantially parallel threads extending continuously in the same direction over the entire length of the sensor and enveloping said sensor all around.

2. A process according to claim 1, wherein encapsulation of a sensor to be placed in a road transversely to the traffic path is performed in a removable mold, said process comprising enveloping said sensor all around with said substantially parallel threads of organic in inorganic material extending continuously and unidirectionally over the entire length of the sensor and embedding the enveloped sensor in a binder composition that hardens by polymerization, so as to obtain a self supporting three-dimensional structural bar detector incorporating said sensor inside the cured embedding mass.

3. A process according to claim 2, wherein said mold has a parallelepiped cross section and said threads are glass threads comprising

filling said mold with said glass threads (8);

positioning the sensor (1) in said mold equidistant over the entire length thereof from a face of the mold;

closing the mold;

injecting said binder composition into the closed mold

so as to obtain, after polymerization of said binder composition and removal of the mold, a resultant bar (7) containing said sensor (1).

4. A composite bar containing a sensor (1) as obtained by using the process according to claim 3.

5. A process according to claim 3, comprising connecting at least one end (5) of said sensor to an electrical connection cable (6), and prior to the positioning of said sensor in the mold, surrounding said sensor with a flexible sleeve (10) for protection of the connection between said sensor (1) and said cable (6), said sleeve (10) extending out of the end of said bar (7).

6. A composite bar containing a sensor (1) as obtained by the process according to claim 5.

7. A process for placement in a road (2) of a traffic sensor in the form of a bar (7) according to claim 2, comprising:

digging, in a road (2), a trench (11) with a cross section considerably greater than the cross section of said bar (7);

providing in bottom (12) of the trench (11), a lower base layer (18) comprising at least one sheet (17) of nonwoven threads (17a) of organic or inorganic material embedded in a hardenable polymeric binder composition containing reinforcing fibers of organic or inorganic material;

positioning U-shaped brackets (19) in the trench, said brackets being suspended by edges thereof (19a) in the road, the bottom of the brackets being flush with the base layer;

in positioning said bar (7) on said brackets (19) resting on the edges of trench (11) to prevent said bar from being driven into said base layer (18) during the hardening of said composition;

covering said bar (7) with an upper covering layer (21) similar to said lower base layer (18);

and applying a finishing layer (22) comprising said binder composition that is flush with road (2).

8. A traffic sensor placed in a road as obtained by the process according to claim 7.

9. Process according to claim 7, wherein said base (18) and covering (21) layers each have at least three layers of sheet (17) of threads (17a).

10. Process according to claim 9, wherein said thread sheets (17) are sheets of glass threads.

11. Process according to claim 9, wherein said reinforcing fibers the composition are glass fibers.

12. Process according to claim 7, wherein said threads sheets (17) are sheets of glass threads.

13. Process according to claim 12, wherein said composition comprises of a charge of glass fiber and sand and a binder having an epoxy resin base that can be polymerized.

14. A process according to claim 2, wherein said threads (8) are glass threads.

15. A composite bar containing a sensor (1) as obtained by the process according to claim 2.

16. A process according to claim 1, wherein said threads (8) are glass threads.

17. A composite bar containing a sensor (1) as obtained by the process according to claim 16.

18. A traffic sensor comprising a self-supporting bar comprising a rectilinear piezoelectric sensor having a longitudinal axis and centered axially in a stratified encapsulating mass which comprises threads, said threads consisting essentially of substantially parallel threads extending substantially parallel to the longitudinal axis over substantially all the length of the sensor, said threads being tightly embedded with the sensor in a cured composition comprising a polymerizable binder.

19. A traffic sensor according to claim 18, wherein the threads have the length of at least one meter.

20. A traffic sensor according to claim 19, wherein said threads have a diameter of less than 0.5 millimeters.

21. A traffic sensor according to claim 20, having a diameter of 1-10 millimeters.

22. A traffic sensor according to claim 21, wherein said threads are glass.

23. A process for placement in a road (2) of a traffic sensor in the form of an encapsulated bar (7) reinforced by substantially parallel threads along the longitudinal axis of said bar, said process comprising

digging, in a road (2), a trench (11) with a cross section considerably greater than the cross section of said bar (7);

providing in bottom (12) of the trench (11), a lower base layer (18) comprising at least one sheet (17) of nonwoven threads (17a) of organic or inorganic material embedded in a hardenable polymeric binder composition containing reinforcing fibers of organic or inorganic material;

positioning U-shaped brackets (19) in the trench, said brackets being suspended by edges thereof (19a) in the road, the bottom of the brackets being flush with the base layer;

positioning said bar (7) on said bracket (19) resting on the edges of trench (11) to prevent said bar from being driven into said base layer (18) during the hardening of said composition;

covering said bar (7) with an upper covering layer (21) similar to said lower base layer (18);

and applying a finishing layer (22) comprising said binder composition that is flush with road (2).

24. A traffic sensor placed in a road as obtained by the process according to claim 23.

25. A traffic sensor according to claim 24, wherein said threads have a length of at least one meter and wherein said fibers have a length of less than one centimeter.