As summer slowly but surely turns to autumn delays caused by leaves on the line will come to the fore. It has become something of a national autumn joke and is seen by the British general public as a very poor excuse for more bad service from Railtrack and the various train operating companies.
The problems of traction and adhesion caused by leaves and other contaminants are however, ones that the rail industry takes very seriously and spends large sums of money on trying to solve. Poor traction and adhesion not only cause inconvenience and delay for the travelling public, but also have serious safety implications, such as signals passed at danger (SPADs) and increased stopping distances. Additionally, there are the financial implications that result from these delays; the train operating companies are heavily penalised for delayed trains and millions of pounds are spent to reduce the contaminant from the railhead. For example, in 1999 Railtrack alone is reputed to have spent £100 million on its autumn treatment programme to remove leaf residue and other material from the tracks.
In the days of steam trains, the problem of “leaves on the line” did not exist. The trees bordering railway lines were regularly cut back to minimise the risk of trackside fires. As diesel and electric trains were introduced, the cutting back was reduced, and often trees were planted to help reduce the noise. The result was the ever increasing amount of contaminant on the railway lines and the resulting delays and other problems.
The traditional rail industry processes of removing contaminants from the rail track are very low-tech. These methods include blasting the tracks with a gel-like material called “sandite”, high-pressure water jets, or scrubbing the tracks. All of these methods are unreliable, slow, expensive and cause additional problems.
Working closely with the rail industry, specifically Railtrack and Railway Safety, as well as being supported by two grants from the DTI’s Smart Award scheme, LaserThor has brought leading scientific laser and optic technology together in a number of world firsts to solve this long-standing and hitherto intractable problem: the removal at speed of leaf and other contamination from the railhead. LaserThor has carried out groundbreaking research in order to understand the dynamics of the problem and therefore help determine how to solve it. Although the leaf problem has been around for many years, the methods of treating railhead contamination have not kept pace with the latest technological developments. Furthermore, the current treatment methods are operationally difficult to manage, are costly, and leave residual problems in their wake.
The laser solution developed by LaserThor uses the world’s most powerful Neodymium Yttrium Aluminium Garnet (Nd:YAG) laser ever built (2.5 times more powerful than any other laser of its type in the world), to deliver 1000 Watts of pulsed laser energy via a very thin fibre optic (another world first) to the Railhead Delivery System, which converts a round beam of light energy into a straight line across the rail (another world first!). The 80 nanosecond pulsed laser beam hits the rail 25,000 times a second. The contaminant absorbs each 5000°C pulse of laser light, causing it to rapidly heat, expand and lift off the rails. The result is a dry, clean track for the trains to run on.
The LaserThor laser unit is mounted on a Multiple Purpose Vehicle (MPV) and the laser beam is delivered to the railhead by fibre optic cable. “We found that it was entirely feasible to use lasers to remove rail contamination without damaging the track” says Higgins.
Using the laser has been proven (over the course of three years of research, development and testing) to be safe, cost effective and to be efficient in the removal of railhead contamination including: leaf residue, oil, grease, water, ice, hydraulic fluid, ice breaker, diesel, petrol, aviation fuel, paraffin, tyre rubber, rust and coal slurry. The railhead is left clean and dry; the contamination problem having been speedily, efficiently and effectively dealt with.
Malcolm Higgins founded LaserThor in 1999 having listened to a radio report about the annual “leaf” problems facing the railway industry. “I am no scientist or railway expert,” comments Higgins, “but it suddenly occurred to me that lasers, which are so common nowadays, ought to be able to help.” The idea was simple, to attach lasers to trains so that they would clean the tracks as they passed along them. A lot of progress has been made since 1999 and working in close co-operation with DERA Malvern, the Rutherford Appleton Laboratories near Oxford & the Fraunhofer Institute for Laser Technology in Aachen, Germany, the final product is near completion. Active marketing to a worldwide market will be started at the forthcoming Railtex 2002 exhibition held at the Birmingham NEC in 26-28 November 2002 (Hall 1, Stand 894).
In the autumn of 2000 and 2001 Railtrack permitted LaserThor to carry out live rail side testing of the laser, which proved the technology could meet the challenge of the task, as well as proving that the track circuits and track itself were not damaged. In addition, LaserThor carried out exhaustive laboratory testing to establish whether exposing the railway track to very intense bursts of laser light in any way damaged it. Several sections of track were subjected to varying intensities and amounts of laser shots and then sent for metallurgical analysis. The results have proved that the operational system does not damage the track. “We are well within the safety range,” says Higgins. Additionally, environmental safety checks have also been carried out to ensure that the laser ablation does not produce harmful emissions.
As a result of LaserThor’s testing and development, which Railtrack and Railway Safety have been closely monitoring, Railtrack is now seriously considering the use of this technology to solve the “leaves on the line” problem in the UK. Other infrastructure railway companies from Europe and North America, that have similar leaf and other contaminant problems, have also been in contact with LaserThor recently. As a result, LaserThor expects interest to be very strong at the Railtex 2002 Exhibition and anticipates that it will be in serious purchasing negotiations with a number of potential customers for delivery of units in time for the autumn of 2003.