Optasense Holdings Limited

Optosense Holdings Limited

Richard Martin

David John Hill

Roger Ian Crickmore

Magnus McEwen-King

Graham Bruce

Jon Richards

This application relates to apparatus and methods for traffic monitoring, especially for monitoring of road traffic flow using fiber optic distributed acoustic sensing. The method involves performing distributed acoustic sensing (DAS) using a suitable interrogator unit () to provide a measurement signal from each of a plurality of sensing portions of a first length of a sensing optical fiber (), where the first length of the sensing optical fiber runs alongside a road () having a plurality of lanes. The measurement signals from the sensing portions are processed to detect vehicles () travelling on the road and to determine at least one detected traffic flow property. The method further involves using a traffic flow model to relate the detected flow property to a modelled flow property, where the traffic flow model is configured to model vehicle detections that will be missed by the distributed acoustic sensing i.e. an indication of vehicles present on the road but not detected by the DAS sensor.

Monitoring traffic flow

The present application relates to road traffic monitoring to detect the number, speed and/or type of vehicles travelling on a road. Noise features () are deployed on, or formed in, the surface of a road (). The noise feature () is arranged to generate a characteristic acoustic signature when traversed by the wheels of a vehicle () travelling within a lane of the road. A distributed acoustic sensor () is deployed to detect occurrences of the characteristic acoustic signature. In some embodiments the noise element may comprise at least two distinct elements (), for instance rumble strips arranged transversely to the road, which are a known distance apart along the road. The acoustic signals from a wheel crossing both elements can be detected and used to determine the vehicle speed. The number of vehicle axles and axle separation can also be determined to categorize the type of vehicle. A plurality of noise features may be located in different lanes of a multi-lane road with noise features in different lanes arranged to generate different characteristic acoustic signatures.

Traffic monitoring

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Farnborough, United Kingdom

Richard Martin