• Leaves on the Line

    The facts 

    Often regarded as a joke, “Leaves on The Line” is now recognised as a serious safety and performance issue, which disrupts rail services during the Autumn – not just here in Britain, but all over Europe and North America. 

    The scale of the leaf-fall problem and the cost of keeping services running smoothly is huge:

    • A mature lineside tree has between 10,000 and 50,000 leaves
    • Thousands of tonnes of leaves fall onto railway lines each year
    • There are 21,000 miles of track to keep clear in Britain and it costs Network Rail approximately £50 million per year to manage the problem
    • The annual cost of lineside vegetation management is between £20,000 and £50,000 per mile

     

    It is impossible to predict exactly when the leaf fall season will start and how long it will last, but the weather can provide a guide to its likely onset and how serious it is likely to be for the railway. 

    A severe leaf fall season often follows a wet summer. It starts with a hard frost, followed by a high wind and a period of dry weather, which causes large amounts of leaves to fall over a short period of time. 

    But traditionally, Autumn is the season of mists and mellow weather, which spreads leaf fall over a longer period and reduces the severity of the problem.

    How do leaves on the line affect trains? 

    Think of leaves on rails as black ice on roads and you’ll begin to understand the nature of the problem. We’re not talking about piles of dead leaves, but a hard slippery layer that coats the rails and is very difficult to remove. Briefly, this is what happens:

    • Leaves are swept onto the track by the slipstream of passing trains
    • Light rain falls
    • Train wheels crush the wet leaves at a pressure of more than 30 tonnes per square inch
    • This compacts and carbonizes the leaves, forming a hard, teflon-like coating on the surface of the rails

     

    Consequently, trains have to operate at slower speeds to ensure safety and to reduce the potential for the wheels to slide on the rails when slowing, and spinning when trying to accelerate.

    This means that drivers have to brake earlier for stations and signals and move off again more slowly - which causes delays to services. 

    How do leaves on the line affect trains? Continued 

    If a train can’t move because its wheels can’t grip the rails, often there is no alternative route, therefore following trains can be delayed or cancelled.

    In addition to causing disruption to customers, the damage inflicted on train wheels during sliding and spinning on rails is considerable and means some trains have to be taken out of service for expensive repair. The rails too can be damaged costing many thousands of pounds to repair each year.

    So what is the rail industry doing about it? 

    Network Rail, the body responsible for maintaining the rail network, is working to eliminate or minimise the problem of leaves on the line:

    • Network Rail has a fleet of 30 special ‘sandite’ trains, which spread a gritty paste on the rails to give trains improved adhesion. It is also investing £1.6 million in new Multi Purpose Vehicles that are fitted with lasers to blast leaf mulch off the track. Known problem areas such as deep cuttings and steep inclines are targeted in order to help minimise delays. 
    • There are also static machines to apply sandite at known trouble spots and mobile applicators, which can be used by track workers. High pressure water jets are also used to remove crushed leaves before they form a hard coating
    • Leaf guards can be positioned around the track to stop the leaves being blown onto the rails
    • In some cases, it is necessary to fell problem trees. 
    • However to protect the environment, these are replaced with smaller leafed trees such as hazel, cherry and holly. 
    • Network Rail’s tree surgeons take advice from conservation specialists to minimise the impact tree management can have on wildlife. For example, no work is planned during the main nesting season.
    • Our fleet of trains is also fitted with sophisticated sanding equipment to improve traction on slippery rails – the equivalent of ABS on a car. The driver can apply the sand when wheel-spin occurs during acceleration