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.

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.

A measuring method for detecting a mechanical force acting on an object using a fiber optic sensor unit is disclosed. At least one measuring channel has a sensor fiber with a fiber Bragg grating embedded in the sensor fiber with a Bragg wavelength and a sensor detection element. The sensor fiber is fixed to the object in the area of the sensor FBG. The method includes coupling light from a light source into the sensor fiber and detecting the light reflected and/or transmitted by the sensor FBG by the sensor detection element. The light source has a wavelength-dependent intensity distribution with an edge. A wavelength change in the Bragg wavelength of the sensor FBG is determined by evaluating a measurement signal which has an intensity change in the detected light intensity of the entire light reflected by the sensor FBG and/or of the entire light transmitted by the sensor FBG.

A fastening element for a sensor is disclosed, which fastening element can be fastened to a structure by means of a light-curing adhesive. The light-curing adhesive is cured within the cavities provided for receiving the light-curing adhesive by direct and/or indirect illumination. Furthermore, a sensor unit having a sensor and a fastening element, an arrangement having a sensor unit and a structure, and a method for providing an arrangement is disclosed.

The present invention relates to conditions monitoring of structures forming part of a transport network, e.g. structural health monitoring of structures, especially tunnels by performing distributed acoustic sensing (DAS) on at least one optical fiber (104) deployed so as to monitor the structure (206) and detecting and analyzing the acoustic response to movement of traffic (205) on the network in the vicinity of the structure to detect the acoustic response (303, 304) of the structure. The acoustic response of the structure is then analyzed to detect any change in condition.

A control system is provided that may include a first sensor configured to detect a vehicle system. The control system may also include one or more processors in communication with the first sensor. The one or more processors may be configured to receive communication related to entry of the vehicle system into an area, and operate the first sensor to begin monitoring the vehicle system in response to entry of vehicle system into the area. The one or more processors may also be configured to record movement data related to the vehicle system, and determine movement of the vehicle system within the area based on the movement data.

A rail-monitoring element includes a carrier on which a strain sensor is attached. The strain sensor may be an optical fiber having a fiber Bragg grating. The carrier has an adhesive layer for adhesive attachment to a rail having a thermally activatable or thermally curable adhesive. The adhesive layer has a heating element having contacts for receiving electrical energy. The rail-monitoring element can be installed more easily and in a manner which saves more energy.

A method for monitoring a railway track (11) is provided, the method comprising detecting monitoring signals (MS) by a distributed acoustic sensor (10) being arranged along the track (11), where each monitoring signal (MS) comprises a monitoring signal value (MSV) for a first measurement segment (12) of the distributed acoustic sensor (10) and a monitoring signal value (MSV) for a second measurement segment (22) of the distributed acoustic sensor (10), determining a first event monitoring signal value (EV1) for the first measurement segment (12) from the monitoring signal values (MSV) that are detected during the passage of a rail vehicle over the position of the first measurement segment (12), determining a second event monitoring signal value (EV2) for the second measurement segment (22) from the monitoring signal values (MSV) that are detected during the passage of a rail vehicle over the position of the second measurement segment (22), and determining a difference value (DV) where the difference value (DV) relates to the difference between an average relative value (ARV) and a relative value (RV), where the relative value (RV) is given by the relative difference between the first event monitoring signal value (EV1) and the second event monitoring signal value (EV2), wherein the average relative value (ARV) relates to an average value of relative values (RV) determined from previous passages of rail vehicles. Furthermore, a monitoring system (15) for monitoring a railway track (11) is provided.