TRACK EQUIPMENT & MAINTENANCE
the heating; it works like a thermostat at home, which is quite neat.
“But, the next part to it, which we’re testing and we’re going to bring in this year, is a remote switch. It means that from our control centres, using weather alerts, we can hit the over-ride and switch the heating on, making absolutely certain there’s no ice on the rail at those locations. We can know via those alerts, ahead of the ambient control sensor, that there’s going to be heavy snow tonight in the Dover area, for example. We’ll switch it on, a couple of hours before service starts, and then we know we’ve got that system in operation rather than just the local control. The system itself has no in-built forecasting technology, so it can’t possibly ‘guess’ what weather is coming.”
Ready for the future
As RTM went to press, the winter of 2011/2012 had not seen extreme snow and ice on the scale of 2010 or 2009, with gales and storms having the bigger impact on the railways. But obviously, the technology needs to be in place in advance so the network is ready for whatever comes.
Ellerby said: “Since October, we haven’t had anything extreme. We’ve had some frost, but nothing that we would expect to have desperately strained the network. Last year was the big test, between Tunbridge and Hastings. Based on the success of that trial – it was successful in terms of clearing the rail – we knew it was worth rolling out further.
Self-regulating heating strips
As well as the temperature sensor and remote switching technology, Network Rail has also experimented with a ‘self-regulating’ strip, produced by Heat Trace, based in Cheshire.
Of the 46km of heated strip in Kent, 16.5km has been of this type.
Ellerby said: “Heat Trace has
primarily been a points heating supplier for us, so this is a new application. We think it will use less electricity, because it’s self- regulating. It’s not constant wattage, so not always on. It works by using two wires opposite each other, with a semi-conductor between them. As it gets hotter and colder the semi-conductor allows less or more electricity through. It is therefore its own control measure, which is a great piece of technology, so it keeps itself at a constant temperature.
“It shouldn’t be on unnecessarily, is the thinking: it won’t be constantly running, heating up the railway. But we need to test that technology, and it does have some other characteristics we’re wrestling with as well.”
“Ultimately, this is about getting trains from point A to the end point at point B. It’s about getting trains moving through the system. It’s not a scattergun approach, it’s about lines of route, so that’s why we’ve tended to focus on Tunbridge to Hastings, so a train can get from its starting point at Hastings all the way up to, for example, Grove Park, and that means trains keep moving and the system flows.
“The roll-out this year has been a further extension to that, on this line of route basis.
“Last year the problem was that we didn’t necessarily have the capability to unblock the whole of the system, and that’s what this year’s work has been about.
“There are a range of measures that have been implemented; not just conductor rail heating in isolation. This on its own will not keep the system moving. We’ve also brought in snow and ice treatment trains, MPV modifications, and other measures. They form part of a package that keeps the system moving.
“You’d have to heat the rail between Dover and Charing Cross pretty well the whole way if you didn’t have all the measures we’re introducing as well.”
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rail technology magazine Dec/Jan 12 | 35
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