Leaves on the Line

Fallen leaves stick to damp rails and passing trains compress them into a slippery layer that reduces grip

 

Britain’s 30,000 hectares of railway land are home to millions of trees, bushes and other plants. A mature tree has between 10,000 and 50,000 leaves and each autumn thousands of tonnes of leaves fall onto railway lines across the country.

Compressed by passing trains, the leaves create a thin, smooth, slippery layer on the rails, so train drivers have to brake earlier when approaching stations and signals to avoid overshooting and accelerate more gently to avoid wheel spin. Leaf mulch can also insulate trains from the rails with the result that the signalling system, which uses electric currents in the track to locate trains, becomes less accurate. To maintain safety, longer gaps must be left between trains, leading to delays. ​​

How the industry is reducing delays caused by leaves

• There are over 50 rail-head treatment trains which clean the rails using water jets and then apply a sand-based gel to help trains gain adhesion
• Each autumn, track teams work around the clock at key locations using descaling machines to clean the railhead (the top of the rails)
• During certain months, 'adhesion forecasts' are received from a specialist weather forecaster. The reports highlight locations that will require action, allowing deployment of resources more effectively
• Modern trains have wheel slip protection which pulsates the brakes to help maintain traction in a similar way to anti-lock braking and traction control systems in cars
• Certain trains have equipment which applies ultra-fine dried sand in front of the train’s wheels to improve traction when braking or accelerating
• Drivers receive refresher simulator training before the autumn season to improve their skills at dealing with slippery rails
• A long-term vegetation management plan which includes the removal of vegetation that is likely to lead to low adhesion. When lineside vegetation is replaced, species which are less likely to shed leaves on to the tracks are used
• Some Train Operators alter their timetables to take account of the increase in journey times caused by the reduction in adhesion each autumn