Train Delays: Leaves on the line, slippery rails and low adhesion
Blog by Jo Farrow
Issued: 15th October 2017 19:52
Updated: 30th October 2019 08:34

Train Delays: Leaves on the line, slippery rails and low adhesion

Written Oct 2017 updated Oct 2019
The nights are drawing in, there is a nip in the air, blustery winds are picking up and the leaves are falling. This is rather annoying in your garden, yet can look beautiful for a countryside walk; however, they are significant safety issues on train tracks. Leaves on the line are the equivalent of black ice on the roads. This can lead to dreaded train delays even cancellations. I had a chat with a train driver, Michelle and also the staff at my local station about this autumnal problem.

The weight of the train squashes the leaves and make a sticky substance causing the wheels to lock up and the train to skid. The speedo goes to zero and it goes quiet, you have no control as the train slides till it gains grip again. This is worse when it is damp or in light mist or drizzle. 

In autumn, the falling leaves lie on the tracks, combining with rain or morning dew, even frost they stick to the railhead. As trains go over this, the surface becomes slippery. This greasy mulch causes issues for stopping and accelerating trains but also affects the signalling systems electric circuits. These circuits identify where trains are on the tracks to keep safe distances between trains. The compressed leaves can subdue the signals and so bigger gaps are needed in between trains, which equals delays.  Many train companies have cut back most foliage and trees at the sides of the railways but the winds and gales from Atlantic low pressures have other ideas. Also, the network passes through many other farms, woods and by private gardens with plenty of leaves and foliage. 

Leaves on the line is very dependant on the weather. All the time there are leaves on the trees this could cause a problem. Day to day weather forecasts are very important throughout Autumn, obviously a windy wet day will cause more problems than a nice dry still day. 

Leaf Busting Trains- In an effort to reduce delays and minimise disruption there are now leaf teams who head out early in the morning to act on 'adhesion warnings'. Forecasts are available predicting when there will be significant leaf fall, usually linked to strong winds and frosts during autumn. Train stations also receive the adhesion warnings by email which highlight low adhesion to the rails that day and how likely it is that trains will be affected.

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Drivers are given extra training for how to drive in the leaf fall season with defensive driving put into action. Brake earlier and harder than normal to assess the railhead conditions, you can visually see the condition of the railheads. There are know areas for low adhesion and drivers will report it if they experience any low adhesion. This is then passed on to other drivers via signallers or word of mouth.

For example, the first train from Glasgow to London Euston has to take it easy on a morning with a low adhesion warning in place. Steadily coming into stations on its way south, with no abrupt breaking. Some trains have equipment to spray ultra-fine sand onto the rails as they move. The rail network has a number of leaf teams, engines which go out and clear and prepare the rails. There are water jets to wash off the leaf gunk and sprays of sandite. This sand-based gel improves the grip between the wheel and the rail. Some areas have rail side applicators of the gel, to help in prone areas.

Train Operators sometimes alter their timetables to take account of the increase in journey times caused by the reduction in adhesion each autumn. This is more likely in the busier parts of the UK where services are barely minutes apart. 

It can be quite scary and unnerving driving through the leaf fall season - Michelle

Network Rail info about Autumn leaves on the tracks

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