Optical sensor system for rail could cut costs and save lives

According to team leader Hwa-yaw Tam, from The Hong Kong Polytechnic University, the fibre accelerometers could be used for real-time monitoring of defects in the railway track or the train to pinpoint problems before an accident occurs. The research is described in Optics Express.

The researchers have spent over a decade developing condition-monitoring systems that use an all-optical sensing network to continuously monitor critical railway components. These systems can help replace inefficient and costly scheduled railway maintenance routines with predictive maintenance based on actual conditions. Systems developed by the researchers have been installed in Hong Kong and Singapore.

"An all-optical sensing network has many advantages as it is immune to electromagnetic interference, has long transmission distance and the sensors don't require electricity," said team member Zhengyong Liu. "However, there is a need for fibre-optic sensors that are optimised to measure different parameters in railway systems."

The fibre-optic accelerometers typically used in condition-monitoring systems are based on fibre Bragg gratings (FBGs) and cannot be used to detect vibrations higher than 500Hz, which is adequate for most railway applications but can't be used to measure the wheel-rail interactions that are a source of track wear.