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Bringing the tram- train to Britain


Other countries have successfully used tram-trains to run on both tram lines and heavy rail routes. Jim Summers FIRO wonders why Britain can’t join the party


A German tram-train from Karlsruhe greets a French TGV under high voltage overhead line equipment


has to go on the roof of a tram. Nowadays the standard tram is a European model, with a profile of a high roof and deep sides, which will necessitate some fiddling with for British clearances. While trams can go round


sharp street corners, it does not automatically follow that they can go round gentle Network Rail curves and, even on tangents, their characteristics can lead to a livelier ride than that offered by Pacers. However, if money is spent on raising the track standard to afford the tram a smoother passage, then the reward is that each six-axle tram will wear the track less than a Pacer would, by a factor of 10.


As the tram wheel has a thinner n


‘In the UK we have a knack of complicating things,’ observed


Professor Rod Smith, as he opened an IMechEE conference on Bringing the Tram Train to Britain. ‘It’s not difficult,’ added Ian Ambrose of Network Rail. The truth of these assertions


was explored by a variety of experts associated with the sole British project for bringing trams onto the heavy rail network between Sheffield and Rotherham. It is only a trial in the UK, and yet the system is well established in Europe. The concept was pioneered


in Karlsruhe from the 1970s, with instant success, leading to the large


PAGE 30 OCTOBER 2010


network of routes where the trams run directly from city streets onto a main line railway. The system in Kassel, with its diesel/electric tram/ trains is currently attracting the greatest attention, but Germany has had its disappointments, and some systems have not progressed. In France, the state railway


will run both trams and trains, and this has facilitated investment and progress. Any problems have tended to be organisational or planning issues, rather than technical ones. Nevertheless, the case in the UK does present some technical issues. For a start, equipment that on a train would go below the solebar


shallower flange than a heavy rail vehicle, it has to be managed to avoid derailment. This is particularly the case at points and crossings, and is easily overcome in most of Europe, where high check rails are the norm. This means that the tram wheel can be given a stepped widening of the back, so that it can bear on the check rail, and guide the wheel through the crossing nose. Low-floored trams may need


different heights at sections of platforms to cater for the disabled. On the other hand, barrow/ foot crossings at rail level can be considered, saving the significant cost of extensive bridges. Detecting the presence of


vehicles has already been addressed


in the UK on the Sunderland extension of the Tyne and Wear Metro, where tracks are shared with the heavy rail trains of Northern. Measures can be devised to minimise the possibility of collisions between trams and trains, such as the provision of TPWS on all signals and double-block working for freight.


A principal mitigating factor in the event of a potential collision on heavy rail infrastructure is the presence of swift-acting and powerful brakes on a tram, needed originally for driving on sight under the free-for-all of highway conditions. Tram brakes can ensure that an erring vehicle is brought to a stand before passing a signal at danger.


This depends on magnetic


track brakes, which might have repercussions on track circuits because of lack of electro-magnetic compatibility. Trams use sanders a lot, which is not desirable in the view of Network Rail, of course. On the other hand, the long-standing problems of light vehicles not registering on track circuits are neatly dealt with in the case of trams by the return path of the traction current through the rails. A trial in UK conditions is


clearly going to challenge traditional ways of thinking, but the prize could revolutionise public transport, just at a time when it is coming under scrutiny once more.


Photo courtesy of Karlsruhe VerkehrsVerbund


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