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A clean sweep
The key to combating leaf fall is to take proactive measures to prevent a slippery leaf layer forming in the first place. This means only one thing: cleaning. Network Rail has dedicated teams who go out at all hours during the season to treat the rails. Multi-Purpose Vehicles (MPVs) have been used effectively on the South West Trains network to clean the tracks for about five years. There are three MPVs based at Eastleigh and another three at Effingham Junction, with a further two on standby. These work continuously throughout the season, pumping high-pressure water jets on to the railhead. There are also 31 static sandite machines strategically placed across the South West Trains network to cover junctions and inclines that have previously been badly affected by leaf fall. These machines release sandite gel (a gritty substance that improves adhesion by giving the wheels something to grip) on to the railhead when a passing train triggers a sensor. In addition, Network Rail's Andrew Humpage and his teams - based at Bournemouth, Eastleigh, Woking, Guildford, Virginia Water and Surbiton - apply traction sand to the railhead using hand-held machines, treating an impressive 520 miles of track every season at 20 key problem areas along the network. Furthermore, all South West Trains' stock (apart from the old slam-door trains) is fitted with automatic sanding devices, which apply sand to the tracks without the intervention of a driver. An on-board computer monitors the rotation of the wheels and automatically releases grit if any fall out of synchronisation owing to slippery conditions.
Rapid response
Despite all the preventative measures taken, incidents do still occur. This requires a reactive strategy coordinated by Wessex Adhesion Control based at Woking. For the entire leaf-fall period, the centre is manned around the clock by four experienced controllers. All the teams and vehicles are tracked via a web satellite navigation system. As soon as a report is received of a train slipping, the controllers know instantly who is closest and can respond most quickly. The site is treated by applying either dry sand or a special liquid called Orange Cleanse, an environmentally friendly mixture that breaks down the mulch, using a tool that resembles a motorised wire brush. Once the rails have been cleaned, the team reports back to control and the line is reopened and a normal service is resumed. "We have to adopt military-style communications in order to direct the right resources to the right locations," explains Paul Arnold, Weather Strategy Manager, Network Rail Wessex Route. "This rapid response helps to minimise delays and service disruption."
Future developments
The next big advance in the fight against leaves on the line will be the use of lasers to burn off any leaf debris on the railhead. "Laser is proving successful," Paul Arnold explains, "but it is still on trial. The main issue that still needs to be overcome is regulating the speed and the sensor so that the machine delivers the right strength at the right place, which is very tricky to determine."
Dealing with leaf fall is becoming increasingly sophisticated and effective, so when you hear that slippery rails or leaves on the line are causing a problem, be assured that it is not a trivial matter, and that lots of people are working hard to keep the railways safe while delivering the best service they can, sometimes under difficult conditions.
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