Train Jams: Leaves on the line

‘Slippery rail’ is a condition suffered by many railway tracks in Autumn and Winter. More commonly known in the UK as ‘leaves on track’ (a phrase that sends dread to a British commuter’s heart), this condition is caused by a mulch of moist, decomposing leaves. The fallen leaves are travelled over by trains, crushing them and releasing pectin (a bio polymer used as a gelling agent in the making of jams). This creates a slippery surface which causes trains to have to slow down, as they have difficultly braking effectively, which causes delays.

In a year, Network Rail has to handle £4.5 million of passenger delay costs, £10 million of track repair, and £5 million of expenditure on vegetation management due to fallen leaves. The trees responsible for the problem were originally planted near railway lines deliberately for their beneficial sound deadening properties!

Technologies are been developed, however, to combat this expensive leaf problem. Train lasers, created over a five year period by Malcolm Higgins (a Royal Navy Lieutenant Commander), were first realised after Higgins listened to a report on train delays on BBC Radio Four and thought that ‘there must be a better way’.

These tiny lasers, attached to train wheels, vaporise leaves on the track. Previous solutions had included everything from hand scrubbing the leaves to using water or sand jets, but these solutions also resulted in damage to the line. The lasers are still in a trial phase, but, due to the short wave length of the beams, the tracks are unharmed by the process. The beams are also more cost efficient and effective than the old water jets. In the initial testing phases, the vibrations caused by the motion of the trains meant that the lasers weren’t accurate enough to hit the leaves. Those used on today’s trains have a higher pulse rate than the originals and used fibre optics.

Aspiring Biology students might wish to investigate the plant properties of pectin further. Those hoping to pursue and academic career in Physics could delve more into the many uses for laser technology. Engineers might be interested in investigating railway engineering work and its causes.