Leaf Fall

Monday, 30 January 2017

Autumn Leaves. So beautiful they wrote a song about them.

Whilst most people will marvel at the natural beauty of autumn, as the leaves turn all colours of the rainbow, to us railway folk these leaves are not at all pretty as they can cause slippery havoc. As a result, we have to operate our Leaf Fall timetable and some mainline services are retimed from Norwich in order to prevent delays further down the route in the morning peak. How exactly is it that leaves can cause such trouble though? Well, that’s what I hope to explain.

As the leaves are gradually broken down by the trains running up and down the tracks, the leaf debris is crushed into a thick hard coating – rather like Teflon – which sticks to both the tracks and the wheels of the train. This leads to a lack of grip between the train and the track in a similar way to ice on the roads in winter. The problem is much worse during foggy or dewy mornings when the moisture level is even higher. In some cases excessive sliding and spinning can damage the wheels to the extent that trains have to be taken out of service while they’re repaired.

The lack of grip, or stickiness, between the wheels and the track means that braking and moving away have to be done much more slowly. So it takes much longer than usual to get up to full speed and drivers have to allow a much larger distance to start braking as they approach stations – rather like driving a car on icy roads. Obviously we don’t want our trains to be slipping and sliding their way through the stations at any time, so we ask our drivers to take extra time and care during the leaf fall period.

In order to allow our drivers this extra time and to make sure our trains are still scheduled to arrive in London at the same time as usual, some of the earliest intercity trains depart a bit earlier, as you may already know.

Thanks for reading – I hope you’re all now experts in the mechanics of leaf degradation and slippery rails and understand why autumn is no laughing matter for us.

What is being done to minimize these delays?

Our colleagues at Network Rail have a fleet of six rail treatment trains which clean the rails day and night using water jets and then apply a sand-based gel to help trains gain traction.

Greater Anglia and Network Rail have jointly invested in a specially-adapted Land Rover, known as a Sand Rover, which will clean and treat the track between Marks Tey and Sudbury, which specialist trains cannot reach. The ‘Sand Rover’ can be driven onto the railway where rail wheels are then lowered onto the rail, turning it into a rail vehicle

All our trains have been fitted with a monitoring system that reports when and where a train experiences slipping. The data will be used by Network Rail engineers to find and clean the affected track as quickly as possible.

Trains on the regional routes in Norfolk and Suffolk will undergo modifications to improve their automatic sanders (that deposit sand onto the rail when the brakes are applied), to prevent the train wheels slipping.

Network Rail will continue to clear lineside vegetation, especially at locations where vegetation might compromise signals and level crossings and in other known problematic areas. Network Rail has worked with land owners to arrange the removal of some of the trees that cause problems at Brundall Gardens Station in Norfolk, and replace them with more ‘railway friendly’ bushes and shrubs that do not shed leaves.

We’ve invested in a mobile wheel lathe at its Crown Depot in Norwich, to fix some of the train wheels damaged as a result of slippery rails without the need to send trains away to other locations. As a result any damaged trains will be out of service for a shorter period, resulting in less disruption for passengers. And we’ve booked additional slots at other wheel lathe locations to fix trains quickly if necessary.