Road traffic monitoring system
First Claim
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1. A traffic monitoring system, the system comprising:
- at least one sensor station comprising at least one optical fibre sensor, said sensor comprising a sensor section and a dummy section, wherein said at least one fibre sensor is an optical fibre, said optical fibre comprising said sensor section and said dummy section, said sensor section having an optical path length less than an optical path length of the dummy section; and
an interferometric interrogation system responsive to an optical phase shift produced in the at least one optical fibre sensor due to a force applied to the at least one sensor station, wherein the interferometric interrogation system comprises a Rayleigh backscatter interferometric interrogation system, wherein said sensor section optical path length and said dummy section optical path length are sufficient to allow interrogation by said interferometric interrogation system.
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Abstract
A traffic monitoring system comprises at least one sensor station (2) and an interferometric interrogation system (9); wherein the at least one sensor station (2) comprises at least one optical fiber sensor (5) deployed in a highway (1); and wherein the interferometric interrogation system (9) is adapted to respond to an optical phase shift produced in the at least one optical fiber sensor (5) due to a force applied by a vehicle passing the at least one sensor station (2).
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Citations
34 Claims
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1. A traffic monitoring system, the system comprising:
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at least one sensor station comprising at least one optical fibre sensor, said sensor comprising a sensor section and a dummy section, wherein said at least one fibre sensor is an optical fibre, said optical fibre comprising said sensor section and said dummy section, said sensor section having an optical path length less than an optical path length of the dummy section; and an interferometric interrogation system responsive to an optical phase shift produced in the at least one optical fibre sensor due to a force applied to the at least one sensor station, wherein the interferometric interrogation system comprises a Rayleigh backscatter interferometric interrogation system, wherein said sensor section optical path length and said dummy section optical path length are sufficient to allow interrogation by said interferometric interrogation system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A traffic monitoring system, the system comprising:
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at least one sensor station comprising at least one optical fibre sensor; and an interferometric interrogation system responsive to an optical phase shift produced in the at least one optical fibre sensor due to a force applied to the at least one sensor station, wherein the interferometric interrogation system comprises a Rayleigh backscatter interferometric interrogation system, wherein the at least one optical fibre sensor comprises a sensor fibre coupled to a dummy fibre;
wherein the optical path length of the sensor fibre is such that the sensitivity of the sensor is low; and
wherein the optical path length of the dummy fibre is greater than that of the sensor fibre such that the combined optical path length of the sensor fibre and the dummy fibre is sufficient to allow the sensor to be interrogated by said interferometric interrogation system, further comprising a casing substantially surrounding at least one of the sensor fibre and the dummy fibre.
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20. A traffic monitoring system, the system comprising:
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at least one sensor station comprising at least one optical fibre sensor; and an interferometric interrogation system responsive to an optical phase shift produced in the at least one optical fibre sensor due to a force applied to the at least one sensor station, wherein the interferometric interrogation system comprises a Rayleigh backscatter interferometric interrogation system, wherein the optical fibre sensor comprises a former and an optical fibre wound on the former;
wherein the former is substantially planar and wherein the sensor is sufficiently flexible such the it is able to substantially adopt the shape of the camber of a highway. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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28. A method for monitoring traffic, the method comprising the steps of:
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providing a plurality of sensor stations on a highway; deploying a plurality of optical fibre sensors at each sensor station; interfacing each optical fibre sensor to an interferometric interrogation system, said interrogation system employing time division multiplexing to monitor an output of each optical fibre sensor substantially simultaneously; and using the output of each optical fibre sensor to derive data relating to the traffic passing each sensor station, wherein the interferometric interrogation system uses a Rayleigh backscatter interferometric interrogation system employing wavelength division multiplexing such that the number of optical fibre sensors which the interrogation system is adapted to monitor is increased. - View Dependent Claims (30, 31, 32, 33, 34)
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29. A method for monitoring traffic, the method comprising the steps of:
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providing a plurality of sensor stations on a highway; deploying a plurality of optical fibre sensors at each sensor station; interfacing each optical fibre sensor to an interferometric interrogation system, said interrogation system employing time division multiplexing to monitor an output of each optical fibre sensor substantially simultaneously; and using the output of each optical fibre sensor to derive data relating to the traffic passing each sensor station, wherein the interferometric interrogation system uses a Rayleigh backscatter interferometric interrogation system, further employing spatial division multiplexing such that the number of optical fibre sensors which the interrogation system is adapted to monitor is increased.
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Specification