by philipmartin
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Railroad Forums
Moderators: Komachi, David Benton
philipmartin wrote:The Severn Tunnel was a GWR project and Brunel had some influence in it. He himself, when a young man, nearly died constructing the tunnel under the Thames.I don't think Brunel had any influence on the design of the tunnel which was built long after his death - and after the gauge of the GWR was changed. Modern practice would have done a thorough geological survey of the route and perhaps would have been able to avoid the water ingress. Probably such a tunnel would have been lower in the ground to avoid the water, and would have been designed to be watertight. It would have resembled the Channel Tunnel in its design. Despite being lower, and therefore subject to greater water pressure, the Channel Tunnel is almost watertight. If a tidal barrage is ever built - something more likely as the need for carbon-free electricity is felt urgently necessary - the tunnel might well be abandoned.
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David Benton wrote:Funny with all the chemical technology today, how hard it is to seal a tunnel or other structure. The difficulty i suspect is that it is already a wet environment, I know in my line of work , we have sealants that we could guarantee will work if the surfaces are dry , but as soon as you introduce a bit of water or oil , it is impossible to seal .I think after 120 years or so if it was possible to seal the tunnel they would have done it. I think there have been surveys. I think a barrage would be the best solution, justifiable as a generator of electricity on a large scale. But I don't think the government is very favourable to that yet. They are not as hostile to the idea as Trump would be but not yet in favour of finding the money.
george matthews wrote:This route is being electrified but electrifying this tunnel is a modern problem. I would be interested to know how they are doing thatAs far as I can recall, at least one of the major tunnels on the route is being electrified with an overhead rail rather than wire for the pantograph to pick up power from. I think that reduces the height, as the rail is solid and doesn't need all the catenary kit which a wire requires.
johnthefireman wrote:I still wonder whether the use of a rail will be more suitable than a normal catenary. The continual showers of water are a serious risk to the electricity.george matthews wrote:This route is being electrified but electrifying this tunnel is a modern problem. I would be interested to know how they are doing thatAs far as I can recall, at least one of the major tunnels on the route is being electrified with an overhead rail rather than wire for the pantograph to pick up power from. I think that reduces the height, as the rail is solid and doesn't need all the catenary kit which a wire requires.
george matthews wrote:The continual showers of water are a serious risk to the electricity.I don't have information on the exact state of the leakage into the tunnel. Is it actually "showers" coming from the roof, or is it leakage down the side walls or seepage around the bottom? Remember that overhead electrification operates outdoors in very heavy rain storms where the masts, conductors and insulators would all be soaking wet for long periods.
johnthefireman wrote:The estuary above is salty. Is the water entering the tunnel also salty? As it is conductive that would be a problem for the overhead.george matthews wrote:The continual showers of water are a serious risk to the electricity.I don't have information on the exact state of the leakage into the tunnel. Is it actually "showers" coming from the roof, or is it leakage down the side walls or seepage around the bottom? Remember that overhead electrification operates outdoors in very heavy rain storms where the masts, conductors and insulators would all be soaking wet for long periods.