It's July 1999 and former Royal Navy lieutenant commander Malcolm Higgins is driving home from London. The radio is on and, somewhere along the M3, the Radio Four presenters start making jokes about Railtrack's excuse du jour: your train was late because there were too many leaves on the line. The on-air conversation ultimately triggers a lightbulb-over-the-head moment that could change the face of modern rail travel.
"I spent the rest of the journey thinking 'this is ridiculous'," says Higgins. "There we were, nearly in the 21st century and they were still sending people out to scrub the tracks by hand.
"I thought about using water jets as a solution and then, a few days later when I was at home, it hit me: lasers."
Having never worked in railways or lasers before, Higgins paid for some research to investigate whether lasers were a viable way of cleaning rail tracks.
When the answer came back affirmative he set up a company, Laser Thor, who spent the next five years developing the laser railhead cleaner. It cost £5m to get from idea to finished product but tests showed it was worth every penny: it romped past its nearest competitor in every test bracket.
So how does it work? How has it developed from a brainwave to a real life product? And why is Network Rail refusing to use it?
Leaves on the line have become something of a running joke, with commuters trying to see the bright side of yet another delayed train, but it is a very real problem. Trees are planted by the side of railway tracks to try and shield local residents from the noise of the trains.
However, this practice comes with a severe downside as once a year, autumnal winds sweep fallen leaves onto the nation's train tracks, where they are mashed into a pulp that becomes as slippery as black ice.
A mature lineside tree has between 10,000 and 50,000 leaves. Britain has 20,000 miles of rail track. Little wonder, then, that keeping tracks clear is a costly business. The annual cost of repairing trains and track from leaf fall is a whopping £10m, while lineside vegetation management costs another £5m.
Perhaps we should just lop them all down? Not unless you want to fork out £20,000–50,000 per mile. There's simply no way around the tree problem.
Every time a train runs over a pile of leaves, they are squashed into a hard, black, shiny, Teflon-like substance that makes it more difficult for trains to slow down and stop. The problem is amplified in bad weather, as the tracks get even more slippery, and it is not unknown for trains to take anything up to 800m to come to a halt. This is obviously dangerous for drivers and passengers alike, so train operators try to remove the mulchy menace.
However, that has proved easier said than done since crushed leaf removal began in earnest in the 1990s. Rail companies tried sending teams of workers out to scrub the tracks by hand and squirting them with sand and gel mixture sandite, before settling on the current method of removal: blasting them with high-pressure jets of water.
TRIALS AND TRIBULATIONS
Whilst the evolution from hand scrubbing to water jets was taking place on the nation's railways, a quiet revolution was taking place on the south coast. From his base on the other side of the M3, Malcolm Higgins instructed his lawyers to file a patent on his idea in 1999 and paid for researchers at the Defence Evaluation and Research Agency in Malvern to test whether lasers could be used to clean rails without damaging the tracks.
"I had approached Railtrack and said 'I think I might have a solution to your leaves on the line problem'," says Higgins. "They thought I was mad, but they agreed to have a look if I could put on a demonstration.
The guys from Malvern fitted a laser onto a Ford Transit van and fired a beam down a drainpipe. There were senior managers from Railtrack there and, when the laser removed the contamination on the rail track, it got them excited."
Although his initial thoughts had proved correct, Higgins realised he needed help to take his idea on to the next stage. With the aid of a private investor, the Rutherford Appleton Laboratory, a £40,000 government SMART award and Railtrack, who helped obtain the necessary safety clearances, the laser railhead cleaner, as Higgins had decided to call it, was ready for its first robust trial in autumn 2000.
However, at the last moment Higgins had serious misgivings about whether the test would be able to take place.
"The Hatfield train crash happened in October and we were meant to go for trials the following week," he says. "Railtrack were in full shutdown mode, not really talking to anybody, but they still insisted we went ahead with the trials."
So, at Effingham Junction in Surrey, a neodymium yttrium aluminium garnet (Nd:YAG) laser, supplied by Spectron Laser Systems, was fitted to a train carriage. Operating at 1,064nm, the laser, aided and abetted by a carefully designed optical set-up of mirrors and lenses, produced a series of minute explosions that cleared debris off the track. The trial was a success: proving that lasers could zap contamination from a rail track, although the train was only moving at 2km/h.
Everything was going swimmingly in theory but Higgins knew that, if his product were going to be adopted by Railtrack, it would have to be able to operate at more realistic speeds. He enlisted the help of the Fraunhofer Institute for Laser Technology in Germany and told them he wanted them to build him a 1kW Nd:YAG laser.
"They were aghast," he says. "Nobody had ever built a laser in that class before. But we knew that there was nothing available that could cope with a railway environment.
"What we did created huge interest around the world. It was an important development, not just for the railway industry, but also for the laser industry."
Fraunhofer built a 1kW Nd:YAG laser that could be fitted into a 1m³ box containing a chiller and electrical power control devices, essential for supporting the new high-powered laser. The laser had a higher pulse rate than the original and used fibre optics to deliver the beam to the track.
The new high-powered laser passed trials in 2002, operating on a train travelling at 20mph. But Higgins knew Railtrack wanted it to be able to operate at twice that speed. So he went back to Germany and enlisted the help of Rofin-Sinar.
LASER RAILHEAD CLEANER
Rofin-Sinar created a monster. The final version of the laser railhead cleaner contains two lasers capable of producing 2kW each. The pulsed energy is channelled via a fibre optic, which delivers a round beam in a straight line across the rail.
The pulsed beam hits the rail 25,000 times per second. The leafy mulch absorbs each 5,000ºC pulse of light, causing it to heat rapidly, expand and lift off the rails. Tests have found that the laser cleaner also works on oil, grease, ice and other problematic substances.
In December 2002 Network Rail, who'd just taken over from Railtrack, signed a contract to take on two prototype laser railhead cleaners. The units were fitted to trains in Guildford in autumn 2003 and Bury in early 2004 for further testing. Operating at speeds of 40mph, the laser railhead cleaner passed all safety checks.
"They were also tested against water jet cleaners and were a huge success," says Higgins. "Trains could stop in a shorter distance on the tracks that had been cleaned by lasers. Water jets could only clean 60 miles of track without changing tanks. Although I believe they can now do 120, ours can do 300 miles in one go. Water jetting costs 3p per mile, while laser jetting costs only 0.03p per mile, making it 100 times cheaper."
By the end of 2004 the safety boxes were ticked, the competition was licked and Higgins was receiving enquiries from all over the world. Then it all went wrong.
According to Higgins, Network Rail stopped returning his calls. He resorted to using a political lobbyist and even had his MP ask a question in the House of Commons to try and get the company to re-engage with him. Eventually, in May 2005, he and his aides sat down with the chairman and chief engineer of Network Rail to talk lasers.
"They accepted that lasers were better than water jets," says Higgins. "They even accepted that lasers would be the preferred method of leaf removal around the world in the fullness of time. But they said they weren't going to take on the laser technology, as they'd invested in water jetting and believed they'd cracked the problem by addressing certain management issues."
For Higgins it means the eight-year £5m project, in which he's invested a lot of his own money, is on hold indefinitely. The worldwide rail industry won't touch a project like this until it is adopted by its host country, he says. So, even though SNCF told him they were very keen on using the technology, they wouldn't take it on until Network Rail had taken it up.
That's not likely to happen anytime soon, according to the company who operates Britain's train infrastructure. "We tried the laser technology but couldn't get it to work effectively enough at the speeds we need it to work at," says a Network Rail spokesperson. "Water jets can operate at a faster speed and we need to be able to clear the tracks as quickly as we can."
So where does that leave Higgins and his laser railhead cleaner?
"I'm immensely frustrated," he says. "I'll contact Network Rail again next year to find out about their autumn performance and see if there's any prospect of reopening talks. The only way I can see that happening is if there's some terrible incidents because of leaf fall and they have a bad autumn. But no one in their right mind would wish for that to happen."