Network Rail Scotland is trialling a new fibre optic, acoustic-based system on the rock fall-prone line between Glasgow and Oban.
The Pass of Brander on the Glasgow-Oban line, which is underlain by clay ground conditions at Ben Cruachan, has suffered several accidents in the last three years due to rock falls caused by bad weather.
The new distributed acoustic sensing (Das) system was installed in February and is reaching the end of a period of recording, isolating and storing background sounds in order to recognise abnormal noises in future, such as rock falls.
Once the system finishes this phase in September, the cables, which are installed mere inches below the ground between the railway and the sleepers, will be ready to alert an interrogators unit when an unknown noise occurs on the line.
The recording will then be passed onto a manned monitoring station based in a signalling centre to check its validity.
The current system, made of horizontal steel trip wires and installed in 1882 by engineer John Anderson, has proven ineffectual in detecting rock falls from lower in the mountain and Network Rail Scotland have been searching for alternatives since 2012.
Replacements such as foot patrols, helicopter flyovers, rock nets, CCTV and removing loose rock periodically were ruled more expensive and less effective, and would result in more track closures in the long run.
This is the first time the cables have been tested on live rail lines and they are currently easy to install and monitor for up to 40km of line. Eventually the Das system will be used to detect many dangers to the rail lines, such as downed trees and other obstructions.