Leaves on the line

1 FEBRUARY 2012

One of those eternally perplexing events for rail and Tube commuters is delays caused by leaves on the line. How can a large piece of metal machinery weighing many tonnes be stopped by paper-thin leaves? It's a common question for people who use parts of the network like the northern end of the Met line in the Chilterns and the east end of the Central Line where it runs through Epping Forest.

Basically leaves on the rails get crushed into a slippery mulch by passing trains. The train wheels can't grip on the mulch. Trains then slide through signals or get flattened wheels and need to be taken out of service. Drivers describe it 'like driving on ice.'

This isn't just a UK problem - in recent years on US commuter lines up to 20% of trains have been out of service in the autumn due to damage from flattened wheels.

So why mention this at the end of winter rather than in leaf-falling October?

We've just had the final stats through for the autumn leaf fall and thanks to a new, much more proactive approach and a new 'Autumn Action Plan' in 2011, we've cut leaf fall related incidents from 2010 by 75%.

This included 'mitigation trains' that spray a sandy paste onto the rails to help the wheels grip, much like gritting snowy sidewalks. Teams were sent to notorious hotspots to hand-clean the rails. Extra vegetation was cut back beforehand. Fundamentally, it meant involving people from different parts of the business to make sure the problem was tackled effectively.

The new trains coming in now on the Met Line will improve this further for next autumn as they are designed from the outset to stop so-called wheel slide.

One of those eternally perplexing events for rail and Tube commuters is delays caused by leaves on the line. How can a large piece of metal machinery weighing many tonnes be stopped by paper-thin leaves? It's a common question for people who use parts of the network like the northern end of the Met line in the Chilterns and the east end of the Central Line where it runs through Epping Forest.

Basically leaves on the rails get crushed into a slippery mulch by passing trains. The train wheels can't grip on the mulch. Trains then slide through signals or get flattened wheels and need to be taken out of service. Drivers describe it 'like driving on ice.'

This isn't just a UK problem - in recent years on US commuter lines up to 20% of trains have been out of service in the autumn due to damage from flattened wheels.

So why mention this at the end of winter rather than in leaf-falling October?

We've just had the final stats through for the autumn leaf fall and thanks to a new, much more proactive approach and a new 'Autumn Action Plan' in 2011, we've cut leaf fall related incidents from 2010 by 75%.

This included 'mitigation trains' that spray a sandy paste onto the rails to help the wheels grip, much like gritting snowy sidewalks. Teams were sent to notorious hotspots to hand-clean the rails. Extra vegetation was cut back beforehand. Fundamentally, it meant involving people from different parts of the business to make sure the problem was tackled effectively.

The new trains coming in now on the Met Line will improve this further for next autumn as they are designed from the outset to stop so-called wheel slide.