Method for monitoring a railway track and monitoring unit for monitoring a railway track

Abstract

A method for monitoring a railway track may include: detecting a first monitoring signal by a distributed acoustic sensor at an initial position while a rail vehicle passes the initial position, the distributed acoustic sensor being arranged along the track; detecting a second monitoring signal by the distributed acoustic sensor at least one predefined position along the track while a rail vehicle passes the predefined position; and comparing the first and second monitoring signals with each other. The first monitoring signal includes features that each relate to one axle of the rail vehicle passing the initial position. The second monitoring signal includes features that each relate to one axle of the rail vehicle passing the predefined position. The comparing includes counting the features relating to axles of the respective passing rail vehicle for the first and second monitoring signals. Furthermore, a monitoring unit may monitor a railway track.

1 . A method for monitoring a railway track, the method comprising:
 detecting a first monitoring signal by a distributed acoustic sensor at an initial position while a rail vehicle passes the initial position, wherein the distributed acoustic sensor is arranged along the track;   detecting a second monitoring signal by the distributed acoustic sensor at least one predefined position along the track while a rail vehicle passes the predefined position; and   comparing the first monitoring signal and the second monitoring signal with each other,   
       wherein:
 the first monitoring signal comprises features that each relate to one axle of the rail vehicle passing the initial position and the second monitoring signal comprises features that each relate to one axle of the rail vehicle passing the predefined position; and 
 comparing the first monitoring signal and the second monitoring signal with each other comprises counting the features relating to axles of the respective passing rail vehicle for the first monitoring signal and the second monitoring signal. 
 
     
     
         2 . The method for monitoring a railway track according to  claim 1 , wherein comparing the first monitoring signal and the second monitoring signal with each other further comprises calculating a correlation between the first monitoring signal and the second monitoring signal. 
     
     
         3 . The method for monitoring a railway track according to  claim 1 , wherein at the initial position the integrity of the rail vehicle passing the initial position is given. 
     
     
         4 . The method for monitoring a railway track according to  claim 1 , wherein the integrity of the rail vehicle passing the initial position is confirmed by personnel of the respective rail vehicle or by an external device. 
     
     
         5 . The method for monitoring a railway track according to  claim 3 , wherein the integrity of the rail vehicle passing the initial position is confirmed for the case that the first monitoring signal comprises the same number of features that each relate to one axle of the rail vehicle passing the initial position as a previous monitoring signal for which the integrity of the rail vehicle passing the position, where the previous monitoring signal is detected, is confirmed by personnel of the respective rail vehicle or by an external device. 
     
     
         6 . The method for monitoring a railway track according to  claim 1 , wherein the distributed acoustic sensor comprises an optical fibre arranged along the track and the monitoring signals are backscattered signals of an input signal which is provided to the optical fibre. 
     
     
         7 . The method for monitoring a railway track according to  claim 1 , wherein the position of a rail vehicle moving on the track is provided. 
     
     
         8 . The method for monitoring a railway track according to  claim 1 , wherein a confirmation signal is provided if the first monitoring signal and the second monitoring signal relate to the same number of axles of the respective passing rail vehicle. 
     
     
         9 . The method for monitoring a railway track according to  claim 1 , wherein a confirmation signal is provided if the first monitoring signal and the second monitoring signal have at least a predefined level of correlation. 
     
     
         10 . The method for monitoring a railway track according to  claim 1 , wherein the at least one predefined position is determined by carrying out a correlation analysis for monitoring signals detected at a plurality of positions along the track during the passage of a rail vehicle with the first monitoring signal, wherein a position along the track is a predefined position if the monitoring signal at the respective position has at least a predefined correlation coefficient with the first monitoring signal. 
     
     
         11 . The method for monitoring a railway track according to  claim 1 , wherein at the predefined position the rail has a defect or an irregularity. 
     
     
         12 . The method for monitoring a railway track according to  claim 1 , wherein the second monitoring signal has an amplitude that is above a predefined threshold and monitoring signals detected during the passage of a rail vehicle at positions different from the at least one predefined position have an amplitude that is below the predefined threshold. 
     
     
         13 . The method for monitoring a railway track according to  claim 1 , wherein the method is carried out for a plurality of predefined positions. 
     
     
         14 . A monitoring unit for monitoring a railway track, the monitoring unit comprising:
 an input that is connected to a distributed acoustic sensor being arranged along the track;   a detection unit that is configured to receive monitoring signals that are detected by the distributed acoustic sensor; and   a comparison unit that is configured to compare a first monitoring signal detected by the distributed acoustic sensor at an initial position while a rail vehicle passes the initial position and a second monitoring signal detected by the distributed acoustic sensor at least one predefined position along the track while a rail vehicle passes the predefined position with each other,   
       wherein:
 the first monitoring signal comprises features that each relate to one axle of the rail vehicle passing the initial position, and the second monitoring signal comprises features that each relate to one axle of the rail vehicle passing the predefined position; and 
 comparing the first monitoring signal and the second monitoring signal with each other comprises counting the features relating to axles of the respective passing rail vehicle for the first monitoring signal and the second monitoring signal. 
 
     
     
         15 . The monitoring unit according to  claim 14 , wherein the monitoring unit further comprises an output at which a confirmation signal is provided for the case that the first monitoring signal and the second monitoring signal relate to the same number of axles.