train tracks leaves

Trains given ability to detect leaves on the line and other ‘hazards’

Image credit: Dreamstime

A system that allows trains to detect “low adhesion hazards”, such as leaves on the line or other issues that could cause the rail equivalent of black ice, has been developed by researchers from Loughborough University.

Low adhesion is caused by the contamination of railways lines by biological, chemical and physical factors, some of which cannot be easily monitored or controlled.

The estimated overall cost of low adhesion to the UK railway industry is estimated at £350m each year, according to the Rail Safety and Standards Board.

A minimum level of adhesion is essential for reliable braking and traction performance, especially for maintaining safety and limiting delays. Changes in adhesion can be very localised, unpredictable and transient. Poor adhesion experienced by one train may not affect following trains at the same location.

The newly developed system will detect low adhesion hot spots in real-time and create an up-to-date map of the UK’s network which shows where any hazards might be. The hope is that the information will allow network operators to react quickly to potential risks, allowing services to run more safely and smoothly.

Lead researcher Dr Chris Ward said: “The network is in danger of low adhesion events occurring at all times and the industry takes the impact of these incredibly seriously.

“Network Rail and the wider rail industry invests huge amounts of money in rail head cleaning, controlling flora alongside lines and forecasting where low adhesion events may occur, but it’s not an exact science and affected areas may only be discovered after an incident has taken place. The areas of low adhesion can often be short-lived and various types of train can react differently to the conditions.

“This new technology, by detecting low adhesion in real-time from in-service vehicles, will allow for a much more accurate picture of where hazards lie on the UK’s huge network of track, which will mean a quicker response - such as defensive driving or railhead treatment - and as a result a safer network with fewer delays.”

The detection system uses established sensing methods to collect data that will then be processed using algorithms. The experimental software should pick up small changes in how the wheels of a carriage respond to different track conditions.

As a train passes over areas of low adhesion, the vehicle moves differently compared to running over tracks with high levels of adhesion.

Signals of the movements are picked up by sensors, that are then processed and turned into an assessment of adhesion level. If required, a warning could be sent to the driver or the wider network users.

Elaine Cockroft, project manager at Network Rail stated: “The future ambition is to add the technology to passenger trains or freight locomotives and so the technology would need to be developed to capture continuous data at a travelling speed of 125mph across the network. This would feed into an up-to-date adhesion map of the network.”

A new 22-month study will see the research team conduct a major test programme at Network Rail’s, Rail Innovation and Development Centre in Nottinghamshire to test their algorithms, this summer.

Artificial low adhesion will be created for the testing programme and measured using state-of-the-art friction measurement equipment from the University of Sheffield.

In October, engineers unveiled a new rail track-cleaning system to remove leaves from lines using dry ice pellets and a stream of high-pressure air which freezes the leaves.

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