A method for assembling a strain gauge arrangement for an axle counter, includes: a strain sensor element; a carrier, to which the strain sensor element is fastened; and a railroad track structure to be monitored. When the carrier is fastened to the structure at least a part of it is kept in an elastically deformed state. The carrier is embodied with a first carrier piece opposing a second carrier piece. The strain sensor element is fastened to the first carrier piece with a first fixing point, to the second carrier piece with a second fixing point, and to neither the first nor the second carrier piece with a central section between the fixing points. At least the part of the carrier is elastically braced by means of a bracing element for when adhesively bonding to the structure to be monitored. Thereafter the bracing element is removed.

A fibre sensing apparatus (100) comprises an interrogation unit (104) to interrogate a sensing fibre with optical radiation, and to detect an optical signal returned from the fibre, and processing circuitry (114). A portion of the fibre may be excited with a test signal. The processing circuitry comprises an assessment module (115) to analyse the optical signal returned from the excited portion of fibre, and to determine at least one operational characteristic of the apparatus based on the detected optical signal.

A strain gauge arrangement for an axle counter has a strain sensor element, a carrier and a railway line structure that is to be monitored. At least one part of the carrier is maintained in an elastically deformed state by the structure when the carrier is secured to the structure. The carrier is formed from a first carrier piece and a second carrier piece, which lie opposite one another at a distance from one another. The strain sensor element has one first fixing point fixed to the first carrier piece, and one second fixing point fixed to the second carrier piece, and a middle section mounted between the fixing points which are not fixed to the first or second carrier piece. The strain gauge arrangement is simple to handle and a drop can be reliably detected and a strain state of the strain sensor element can be predetermined more easily.

This application relates to methods and apparatus for distributed fibre optic sensing and especially to the processing of signals derived from such sensing techniques to characterise events of interest. The application describes a method of distributed fibre optic sensing, comprising; performing distributed fibre optic sensing so as to generate at least one set of measurement signals from each of a plurality of sensing channels of an optical fibre (101) in response to at least one event of interest. For each set of measurement signals, processing the measurement signals from different sensing channels according to an association metric to determine whether any sensing channels are associated with one another and form at least one association matrix indicative of the sensing channels that are associated with one another. The method further comprising performing distributed fibre optic sensing to acquire a further set of measurement signals from said sensing channels in response to a further event of interest and processing said further set of measurement signals based on said at least one association matrix to characterise said further event of interest.

A method of mounting a rail monitoring member/element at a mounting location of a rail for rail traffic, in particular on a railway track, is disclosed. The rail monitoring member includes a strain sensor member with a carrier on which a strain gauge, being an optical fiber with a fiber Bragg grating, is fixed. The method steps include: determination of the temperature of the rail and/or rail monitoring member at the mounting location; checking whether the determined temperature is within a predefined temperature interval; providing heating or cooling application to the rail and/or rail monitoring member at the mounting location, if the determined temperature is not within the predefined temperature interval; positioning and adhesively fixing of the carrier of the rail monitoring member at the mounting location. The method can be carried out easily and allows reliable and accurate monitoring of the rail using a strain sensor member.

A strain gauge arrangement for an axle counter has a strain sensor element, a carrier and a railway line structure that is to be monitored. At least one part of the carrier is maintained in an elastically deformed state by the structure when the carrier is secured to the structure. The carrier is formed from a first carrier piece and a second carrier piece, which lie opposite one another at a distance from one another. The strain sensor element has one first fixing point fixed to the first carrier piece, and one second fixing point fixed to the second carrier piece, and a middle section mounted between the fixing points which are not fixed to the first or second carrier piece. The strain gauge arrangement is simple to handle and a drop can be reliably detected and a strain state of the strain sensor element can be predetermined more easily.

This application relates to methods and apparatus for distributed fibre optic sensing and especially to the processing of signals derived from such sensing techniques to characterise events of interest. The application describes a method of distributed fibre optic sensing, comprising; performing distributed fibre optic sensing so as to generate at least one set of measurement signals from each of a plurality of sensing channels of an optical fibre (101) in response to at least one event of interest. For each set of measurement signals, processing the measurement signals from different sensing channels according to an association metric to determine whether any sensing channels are associated with one another and form at least one association matrix indicative of the sensing channels that are associated with one another. The method further comprising performing distributed fibre optic sensing to acquire a further set of measurement signals from said sensing channels in response to a further event of interest and processing said further set of measurement signals based on said at least one association matrix to characterise said further event of interest.

In a particular implementation, a vehicle detector configured to detect a train entering a work zone includes a detector portion including one or more motion detectors. The one or more motion detectors are configured to detect a vehicle entering a work zone. The vehicle detector also includes a vertical member coupled to the detector portion. The vehicle detector further includes a stabilizing structure including one or more components configured to stabilize the vertical member. The one or more components define a circumference around the vertical member.

A train detection system for a railway track section placed on a track bed, the track section having two rails, the train detection system comprising at least one cable, the cable being placed across the two rails, a transmitter connected to the cable and configured to emit an emitted signal into the at least one cable, a receiver connected to the cable and configured to receive a received signal related to the emitted signal having passed through the cable, and capable of determining, according to the received signal, between an unoccupied state where no railway vehicle is present on the track section, and an occupied state where the track section is occupied by a railway vehicle. The cable is buried under the track bed.

An axle-counting method for railbound vehicles includes the following method steps: coupling light into at least one sensor fiber, wherein the sensor fiber includes at least one fiber Bragg grating mounted on a rail, wherein each fiber Bragg grating has a reflection spectrum having a reflection peak which is at a Bragg wavelength and has a full width at half maximum; generating a difference signal from two shear stress signals through detection and filtering the temporal intensity course of the light power reflected by two Fiber Bragg gratings which are arranged at a separation from one another; and generating a wheel signal if the difference signal exceeds a predetermined shear stress difference limiting value.