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Frequently Asked Questions |
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1st question: I am currently studying for a BSc (Hons) Degree in Construction Engineering at Napier University. My honours project is to design a prestressed bridge suitable for a tram network. As part of this, I am currently investigating the proposed tram system to be installed in Edinburgh. I would there for be extremely grateful if you could forward to me some technical details of the tram systems that you supply, in particular I am interested in the city class tram and its axial loads. If you need to clarify anything please do not hesitate to contact me. Regards, Paul Sharpe Answer: Dear Paul, Your enquiry has been passed to me for answer. For a large structure like a bridge rarely is axle load the key factor but rather the total load. If the bridge in question is 30 m long, then the maximum loading will be two trams simultaneously passing in opposite directions. Axle loads are critical for the track design, the purpose of which is to distribute the load into the bridge structure. I will come back to track design. You may need to consider dynamic loads, which will depend partly on tram suspension characteristics, and partly on whether the tram will normally start or stop on the bridge. If this is a section of track where tram coasts, then the dynamic loads will be relative small compared to the static load of the trams. The industry standard for light rail is a maximum axle load of 10tonnes. This is akin to the maximum road vehicle axle loading, for the obvious reason that many tramways also operate in public highways and therefore must not over stress the pavement structure. I have tabled below key figures for UK tramways, and a comparison with the City Class tramcar:
You will see that dividing weight by No. of axles is less than 10 tonnes in all cases. However all these vehicles will have at least one axle, which when the vehicle is fully loaded, will be 10 tonnes. If you are looking at bridge deck design, why not incorporate the LR55 track system? This will give a better load distribution, you may be able to have a thinner deck section, the finished bridge will have a smooth surface ( good for emergency evacuation or for maintenance vehicle access ) and by having a resilient track system, will be quieter. I hope that this helps. Sincerely, Professor Lewis Lesley Technical Director, TRAM Power Ltd. |
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Q2 Do you happen to know how long a stretch of track you would need to drive a tram up to 30mph and then bring it to a complete stop? Thanks again. Steve. Answer: When we were testing the City Class tram in Birkenhead last autumn, we did this in about 120m everyday. I would be happy to discuss on the phone (mobile 07976 040 618) Lewis Lesley, Technical Director. |
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Q3 I have a general enquiry relating to trams and light rail and was hoping you may be able to help. When setting up a tram network in a city is it necessary to provide a dedicated test track to train drivers and/or test vehicles, or are these needs generally met by the actual network. Thank you very much in advance for your help on this matter. Best regards, Steve. Answer: Dear Steven, Normally the manufacturer test the trams on their own test tracks, prior to delivery. Driver training can be either at the test track or on the actual network. Route familiarisation training has to be done on the actual network. Final testing is done on the actual network, to check for damage in transit and compliance with signalling and information systems If it is a new network then vehicles are required to help with testing the network infrastructure. However, it is important that these "Test" trams have been pretested on the manufacturers test track to ensure that any problems found on the new network are due to the network and not the vehicle !!! Vaughan Smart |
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Q4 Hi, my name is Phuong Nguyen, and I am a student at San Diego State University, San Diego, California, USA. Our civil engineering design class is doing a presentation on the feasibility of having a tram system in downtown San Diego. Do you happen to have any information on the initial cost and estimate operating cost for such a system? i.e. cost of a tram, cost per mile of rail and cable line etc. thanks Phuong Answer: Dear Phuong Nguyen, Thank you for your email about a possible tramway in San Diego. Your questions are very wide, and of course San Diego already has a light rail system. Do I suppose that you mean low floor vehicles with low height platforms (8 - 10") to give level boarding for passengers under the ADA requirements ? To help you, we will need a lot more information, eg
Yours sincerely, Professor Lewis Lesley Technical Director |
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Q5 I am studying mechanical engineering at Edinburgh University and as part of a transport project I am researching the efficiency of urban vehicles such as trams from an aerodynamic design point of view. I can't find any information on your website relating to this issue, e.g. drag coefficients or more general information in this area. Can you help? Regards Sean Answer: Dear Sean, It is not surprising that there is little literature on the aerodynamics of trams. For such "solid front" rail vehicles aerodynamic friction does not exceed rolling resistance until over 160km/hr. Few trams operate that fast, typically with a maximum speed of 80km/hr. Even if they did run at 160km/hr, there is one other energy absorbing behaviour of trams, which is larger than the rolling resistance, and that is the energy used to accelerate from frequent stops, typically about every 400m, or once every two minutes. So research has been concentrated into the energy using areas which are critical, especially reducing the energy for acceleration (KE= 0.5*M*V*V), and trying to capture energy during braking, rather than wasting brake heat into the atmosphere. The University of Manchester did a project in 2006, when we were test running our prototype City Class tram on the Blackpool tramway. They found that a Blackpool tram (weighing 18tonnes) used about 1.5kWh per km. In comparison the City Class (22tonnes) was about 1.0kWh per km. Even tube trains in tunnels with small clearances use more energy accelerating than in overcoming air resistance. The first engineer to experiment with reducing aerodynamic resistance was Sir Nigel Greasley in the early 1930's, who wanted to have faster (and more economic) express passenger trains. So he designed light weight coaches, and wind tunnel tested the streamlining for his new A4 Pacific steam Locos, the most famous of which is Mallard that set the world steam speed record of 126mph in 1936. It still stands today, although the rail speed record is held by the French with an electric TGV set running at 505km/hr in 2001. At a different level, air resistance exceeds the rolling resistance of bikes at about 30km/hr, so serious cyclists go to extremes to streamline themselves. I hope that will be of some use for your studies. Sincerely, | |||||||||||||||||||||||||||||||||||
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TRAM Power Ltd
Registered office:
99 Stanley Road
Bootle
Merseyside
L20 7DA
England
Email : marketing@trampower.co.uk
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