Traffic monitoring

• US 7,068,186 B2
• Filed: 02/12/2002
• Issued: 06/27/2006
• Est. Priority Date: 02/15/2001
• Status: Active Grant

• Current Assignee: Optasense Holdings Limited (Luna Innovations, Inc.)
• Original Assignee: Qinetiq Limited (QinetiQ Group PLC)
• Inventors: Hill, David John, Thomas, Sean Dormer
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): MEHMOOD, JENNIFER
• Application Number:
  US10/468,064
• Publication Number:
  US 20040061628A1
• Time in Patent Office: 1,596 Days
• Field of Search: 340933-943, 200/86.R, 200/86.A, 200/85.R, 359234-236, 359/6, 359/11, 385/10, 385/2, 455/506, 398/98, 398/84, 398/87, 398135-172, 701117-122
• US Class Current: 340/942
• 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 1/01 Detecting movement of traffic to be counted or controlled G08G1/07 - G08G1/14 take precedence
• 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

The present invention provides an optical fiber sensor for traffic monitoring, which comprises a former consisting of an elongated plate, and an optical fiber wound onto at least one surface of the elongated plate. The elongated plate is flexible in a direction transverse to the at least one predetermined property of an optical signal transmitted through the optical fiber sensor. The resulting sensor has a reduced depth which makes it easier to locate within the surface of a traffic route, has increased flexibility to enable to confirm to the surface of the traffic route, and has good cross axis sensitivity rejection.

Claims

1. An optical fibre sensor for traffic monitoring, comprising:

a former comprising an elongated plate; and

an optical fibre wound onto at least one surface of the elongate plate, the elongate plate being flexible in a direction transverse to the at least one surface such that passage of traffic over the optical fibre sensor is arranged to cause a variation in at least one predetermined property of an optical signal transmitted through the optical fibre sensor.

2. An optical fibre as claimed in claim 1, wherein the elongate plate is provided with a pair of curved elements which protrude from the at least one surface and are spaced from each other along the elongate axis, wherein the optical fibre is wound longitudinally between the curved elements.

3. An optical fibre sensor as claimed in claim 2, wherein each curved element is rotatable about an axis transverse to the at least one surface of the elongate plate.

4. An optical fibre sensor as claimed in claim 2, wherein each curved element comprises a spindle.

5. An optical fibre sensor as claimed in claim 4, wherein the spindle is fixed and the curved element further comprises a wheel rotatably mounted on the spindle.

6. An optical fibre as claimed in claim 2, wherein the pair of curved elements are located towards opposing ends of the elongate plate.

7. An optical fibre as claimed in claim 2, further comprising a pair of termination plates provided towards opposing ends of the elongate plate, each termination plate being couple to a corresponding one of the curved elements so as to guide the optical fibre to and from that curved element.

8. An optical fibre sensor as claimed in claim 2, further comprising one or more guide members protruding from the at least one surface of the elongate plate and positioned between the pair of curved elements, the guide members being arranged to guide the optical fibre along a predetermined path on the at least one surface between the pair of curved elements.

9. An optical fibre as claimed in claim 8, wherein the predetermined path is a central path along the elongate axis of the elongate plate.

10. A traffic monitoring system, the system comprising:

at least one sensor station; and

an optical interrogation system;

wherein the at least one sensor station comprises at least one optical fibre sensor as claimed in claim 1, the least one optical fibre sensor being deployable in a traffic route;

wherein the optical interrogation system is adapted to respond to the variation in said at least one predetermined property produced in the at least one optical fibre sensor due to a force applied by a unit of traffic passing the at least one sensor station.

11. A system according to claim 10, wherein each sensor is deployed beneath the surface of the traffic route.