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ENVIRONMENT & SUSTAINABILITY


Students from London’s Southbank International School have spent months working on a rail challenge as part of the Engineering Education Scheme, trying to solve a tricky environmental problem.


T


here is no foolproof solution to the problem colloquially known as ‘leaves


on the line’, causing slippery rails, loss of traction, and consequent interference with normal services. Common mitigation measures include blasting the compacted leaf matter off the rails using jets of water and simply chopping down nearby trees – the former being only a short-term solu- tion, and the latter often politically unac- ceptable to local people.


Coming up with a solution to this problem was this autumnal challenge set by Net- work Rail graduate engineers to teenage students taking part in the Engineering Education Scheme.


Bruce Duxbury, the design and technology teacher co-ordinating the scheme at South- bank International School, said it was a real challenge for the Year 12 pupils taking part.


He explained: “They started with the re- alisation that they either had to react to the leaves that are on the line, or prevent them reaching the line in the first place.


“They began exploring preventative solu- tions, such as building tunnels around the worst-affected areas, putting nets up under the trees, and even making nets that would attach to trees and grow with them, and coverings to stop the leaves landing. They also considered chopping trees down!


“Reactive solutions they considered were things like attachments to the train, such as some sort of scraper on the front, or a grinder, or the Japanese rail solutions. Why do we never hear about this prob- lem abroad? They did look into that; the French, for example, appear to either cut down their trees or build fences. The stu- dents went as far as thinking of even flame- throwers to destroy the leaves, or getting people on community service to scrape the tracks. That idea actually had some merit – but it wasn’t an engineering solution, so it was discarded.


“Modifying trains wasn’t possible because this was a problem set for them by Network Rail, not a train operator, and Network Rail aren’t able to just chop down trees they don’t own, and some are covered by tree protection orders, and they’d also have the environmental lobby to deal with.


46 | rail technology magazine Jun/Jul 11


“So, they had a massive brainstorming ses- sion considering all of these solutions, and they decided to go for a preventative solu- tion. It became clear that nets would have to grow with the trees and would actually pull the trees towards the railway in many cases. The cost of tunnels was unfeasible, so they decided on small-scale track cover- ing solutions.


“They went to Huddersfield University where they assessed the best ideas and did some cost-benefit analysis. They were do- ing some work on junction solutions while they were there anyway, and so had some track to work with. They looked at different ways of covering the track, and found the problem was the fail-safe – if you’re cover- ing the track in any way, there’s always a chance the train’s going to hit it.


“So they decided on a retractable cover that just covers the track, but is guaranteed to be out of the way when a train comes. They went through lots of different solutions, and came up with a weighted ‘roof’ over each rail, installed over the most-affected areas, which could be retro-fitted onto the sides of existing track. It would naturally be open because of its weight – assuming gravity never gives up on us – and would be closed using electro-magnets powered by a system they never quite got as far as describing, but that would be shorted out whenever a train crossed into the preced- ing section, opening them up to let it pass. But if anything ever went wrong, they would default to being open.


“The whole process took place over six months of trial and error, with detailed calculations about the weight of the cov- ering and the mechanism, getting electro- magnets to work over varying distances, and so on.”


How much guidance were the students giv- en by the Network Rail engineers?


Duxbury explained: “Initially they ex- plained the problem, but the kids were being treated as engineers, so there was as little explanation as we could manage. That left it up to them to investigate the facts, and the engineers could then drop in ques- tions that would steer the debate, and let them know there were things they needed to be considering, without just saying ‘no, you can’t do that’. We wanted them to have free rein.


“It also gave Network Rail the chance of putting fresh minds to work on something and potentially even getting answers no- one’s thought of.”


The students selected to take part were those already enthusiastic about engineer- ing, and of the team of five, two have now applied for engineering courses, and an- other wants to pursue engineering-related mathematics.


Duxbury said that was a great result, add- ing: “It certainly hasn’t switched them off from being engineers, and now they’ve got an actual project in their portfolios.


“At the very end of the process, they had to present their whole idea to professional engineers who assessed it on a pure engi- neering level, without costing the feasibil- ity as such. That side of it came back from the Network Rail engineers, who said that they had come up with an interesting idea that had never really been considered – and that it was feasible – but that it was too prone to vandalism.


“That’s a very big stumbling block for it. But they thought it was a fantastic piece of work that they would look at. The students discuss in their own report where it could potentially be taken from here.”


FOR MORE INFORMATION Visit www.engineering-education.org.uk


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