Leaves on railway track

Network Rail puts its laser on leaves on the line

Close up shot of leaf placed on line during autumn test October 2022 (image Network Rail)2022, Network Rail

British infrastructure management agency Network Rail is hitting the age old problem of leaves on the line with a space age solution. It’s a death ray for detritus that might finally see railway technology win the annual battle of autumn. The wrong kind of leaves might just be beaten by the right kind of laser on the line.

Never mind snow, sun and strikes. If there is one thing guaranteed to bring Britain’s railways to a standstill. It’s leaves. Come autumn, when this green and pleasant land turns ruby red, railway engineers turn an equal shade of exasperation as the rails are buried beneath a rusty carpet of friction free fallen leaves. Maybe just now they have the answer, in a technology that’s found a hundred and one uses to date – and now the trusty laser has found use number one hundred and two.

Thwarted by nature

Brake shoes once were the answer. The application of friction on the flange provided a self-cleaning mechanism that put leaves in their place – which wasn’t on the line. Trouble is, a trusty brake shoe might cut through the fallen leaves, but it hardly cuts the mustard when you’re trying to stop an 800 tonne train doing 125 miles per hour (200 kilometres per hour). To stop at Ashford you’d have to brake at Sevenoaks.

Super-stopping disc brakes do the job much more reliably, but are thwarted by nature, every time the line gets a carpet of fallen leaves. Pile on the brakes at Priory and you’ll be Dover and out as you fly over the White Cliffs at undiminished velocity. Something better is needed, and plenty has been tried.

The battle to rule the rails

Jets of water; jets of steam; sprays of sand and grit and all sorts of chemically complicated pastes have been tested and tried. They’ve all come up short on providing the ultimate answer to the relentless rustic crust of leaves on the line.

Until now. The technology that powers everything from printers to power stations could finally win the battle to rule the rails come autumn time. What Network Rail is calling space-age technologies, using lasers and plasma jets, are being trialled as a more sustainable way to vaporise autumn leaves from railway lines and minimise passenger delays in the future. We’ll overlook the fact that the technology pre-dates the space-age and doesn’t actually vaporise anything.

Throughout October, Network Rail has been carrying out comprehensive testing using its multi-purpose vehicles (MPVs) on heritage railway lines at the East Lancashire Railway in England. Engineers have been testing if autumn treatment trains, fitted with the laser beams and superheated plasma jets, are as effective at cleaning rails as the current method using high pressure water systems. So far, so hi-tech.

A joke that’s no joke on the railway

During autumn train wheels compress leaves onto rails and form an almost friction-free residue which makes it harder for trains to brake or accelerate (pretty much the two fundamental things engineers would like a train to do). “Leaves on the line are often seen as a joke on the railway”, said Suhayb Manzoor, Network Rail’s project engineer, who doesn’t see the funny side of the matter. “They can cause serious problems and we’re always looking at new ways to tackle this age-old problem.”

Laser used to zap leaves on the track
Underside of the leaf laser train (Network Rail)

The conundrum is not unique to Britain. Railways all over the world suffer issues when trees shed their leaves. “For that reason, it’s exciting to be putting some of the newest technology out there to the test”, adds Manzoor. “The hope [is] that one day it could help Network Rail keep passengers and freight moving safely at this operationally challenging time of year.”

Stars in this war on the rails

Network Rail is not putting all its autumn apples in one basket. They’re trying out two systems because … reasons. The first comes from Laser Precision Solutions, a company that’s pinned their hopes on their ‘LaserTrain’, which uses three high powered beams per railhead to treat the rails. They claim their sophisticated setup will ablate the contamination without melting the rails – which engineers agree would be a significant disadvantage.

Then there’s PlasmaTrack. Their boffins use direct current (DC) plasma technology “which uses heat and active electrons to split things apart. The high energy electrical plasma beam tears apart the leaf layer as well as heating and burning it off.” In other words – they zap the leaves with a zillion volts and try not to do the same to the train and everybody in it – which engineers agree would be a significant disadvantage.

Will it be lasers or plasma that defeats the all-powerful leaf? Currently a fleet of trains with high-pressure water jets clear Britain’s 20,000-mile railway network in the autumn. If a less wet solution, contraction not withstanding, should be found on the rebellious rails of the East Lancashire Railway, expect the empire of Network Rail to strike back soon. That, engineers agree, would be a very poplar outcome indeed.

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Author: Simon Walton

Simon Walton is UK correspondent for RailTech.com and Railfreight.com

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