Crispy
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The expert in the story says the same. I found this cross section of the tunnel
I can't find a simple reference for the standard height of overhead wires in the uk
Electrifying the GWR
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I can't find a simple reference for the standard height of overhead wires in the uk
Crispy
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It's for drainage, apparently.
Exhaustive history and information on the tunnel here: http://mikes.railhistory.railfan.net/r086.html
Exhaustive history and information on the tunnel here: http://mikes.railhistory.railfan.net/r086.html
I'm assuming it's one of these recession driven Great Public Works (which do make some economic sense) - do some long-term infrastructure investment while labour rates are cheap and get the unemployment numbers down a bit, hand out some money to potentially deprived parts of the country in equipment supply contracts, and everyone's (quite) happy.
I remember reading a thing about the Severn Tunnel and thinking that it'd be a nightmare to electrify, because it's simply so wet. Perhaps the imperative of getting the catenary to Cardiff will give someone the will to solve a problem that hasn't been solved in 150 years?
I've always assumed that one of the major arguments that would be made in favour of this tidal barrage thing was the benefits it offered as a transport corridor, too. And, if I were quite keen on that barrage, and didn't mind some incidental improvements in rail connections to Wales, I might come up with the idea of offsetting the projected (presumably huge) cost of getting wires through the Severn Tunnel) against the projected cost of the barrage and selling the whole package - rail link AND tidal barrage, hey, we'll even supply the power to the rail link over the barrage
- as a great big cost saving...
But nobody'd be that machiavellian, would they?
(and, although the wildlife wouldn't much like it, the idea of a massive tidal barrage is quite a neat one, especially with a railway going over the top of it.
I remember reading a thing about the Severn Tunnel and thinking that it'd be a nightmare to electrify, because it's simply so wet. Perhaps the imperative of getting the catenary to Cardiff will give someone the will to solve a problem that hasn't been solved in 150 years?
I've always assumed that one of the major arguments that would be made in favour of this tidal barrage thing was the benefits it offered as a transport corridor, too. And, if I were quite keen on that barrage, and didn't mind some incidental improvements in rail connections to Wales, I might come up with the idea of offsetting the projected (presumably huge) cost of getting wires through the Severn Tunnel) against the projected cost of the barrage and selling the whole package - rail link AND tidal barrage, hey, we'll even supply the power to the rail link over the barrage
- as a great big cost saving...But nobody'd be that machiavellian, would they?
(and, although the wildlife wouldn't much like it, the idea of a massive tidal barrage is quite a neat one, especially with a railway going over the top of it.
Crispy
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Trouble with the tunnel is that they ran across a pretty major freshwater spring whgen digging it. It needs continuous pumping, all day and night or the tunnel would rapidly fill with water.
I'm still not convinced it can be done cheaply. The Intercity Express trains are supposed to have a hybrid deisel/electric model (full of compromises of course) so I'll put good money on the electrification stopping either side of the tunnel, with deisel traction inbetween.
I'm still not convinced it can be done cheaply. The Intercity Express trains are supposed to have a hybrid deisel/electric model (full of compromises of course) so I'll put good money on the electrification stopping either side of the tunnel, with deisel traction inbetween.
I think they did succeed in doing something for some of it which made it a lot less wet. Which might matter less if there were loads of clearance, but I suspect you can't cwtch 25kV overhead up to within 10cm of a completely dripping wet roof in the rest of it without expecting a certain amount of zappage.
And 3rd rail is going to be completely out of the question for pretty much the same reason, except that we're talking about groundwater, of which there is even more.
Perhaps the trains just need to accelerate to enormous speeds before entering the tunnel and just coast through, picking up the wires at the other end
That or carry batteries - great banks of those new fast-charge lithium-ion jobs, maybe?
teuchter
je suis teuchter
Or they can just drive into it really fast and hope they make it to the other side.
What specifically is the problem with the electric/damp thing though? All OHLE is exposed regularly to rain anyway.
I am sure I read that when they had trouble with the major spring when they were digging the tunnel, after the second time it defeated the pumps they finally diverted the spring away from the tunnel and solved the problem. The fact that there is a lot of moisture in the tunnel in any case, because of being under the river does not favour overhead live wires though.
I think the solution to parts of an electrified line not being readily electrified might be with changes to the engines. With something as large as a train engine it should be possible to incorporate a fuel cell battery of some kind. This could be used to provide power for short parts of the journey where the overhead gantry was missing. Or even in an emergency when there is a power cut. The weight problems of fuel cell batteries for use in cars would be reduced as you scale up to the weight of a train engine. It wouldn't be any heavier than a diesel-electric set up which would be a less environmentally sound alternative even when used for part journeys.
I think the solution to parts of an electrified line not being readily electrified might be with changes to the engines. With something as large as a train engine it should be possible to incorporate a fuel cell battery of some kind. This could be used to provide power for short parts of the journey where the overhead gantry was missing. Or even in an emergency when there is a power cut. The weight problems of fuel cell batteries for use in cars would be reduced as you scale up to the weight of a train engine. It wouldn't be any heavier than a diesel-electric set up which would be a less environmentally sound alternative even when used for part journeys.
teuchter
je suis teuchter
This reminds me of an idle thought I had a while ago.
I was wondering whether, once we have a suitable fuel cell technology, you could largely do away with the overhead lines and just have them in short sections where the train could charge up its batteries. You could have these in stations where the train is going to stop anyway. You would do away with lots of overhead line which would remove substantial maintenance costs, and you could keep the weight of the fuel cell on board the train low because it would only need a station-station range rather than one that would allow a full day's running.
Obviously you would need to be able to charge the cells very rapidly.
I was wondering whether, once we have a suitable fuel cell technology, you could largely do away with the overhead lines and just have them in short sections where the train could charge up its batteries. You could have these in stations where the train is going to stop anyway. You would do away with lots of overhead line which would remove substantial maintenance costs, and you could keep the weight of the fuel cell on board the train low because it would only need a station-station range rather than one that would allow a full day's running.
Obviously you would need to be able to charge the cells very rapidly.
Crispy
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Because the wet tunnel lining will also conduct electricity.
As for batteries, we should be able to do a back of the envelope calc. What's the power rating of a train through the tunnel (limited to 90mph) and what's the energy density of the best batteries?
teuchter
je suis teuchter
Crispy
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and water would run down the insulatorsBut you would insulate the cable from the tunnel lining.
teuchter
je suis teuchter
Fix umbrellas to the insulators.
cybertect
It's grim up north (London)
I think that would be a significant problem. You get maybe one or two minutes at a station?
You've got to deliver all the energy that a train's going to use over perhaps the next 40 miles (e.g. Reading to Swindon) of high-speed travel in that short time frame. A massive load in a short period and you also have to deal with all the heat that could be generated by doing that.
teuchter
je suis teuchter
I think that would be a significant problem. You get maybe one or two minutes at a station?
You've got to deliver all the energy that a train's going to use over perhaps the next 40 miles (e.g. Reading to Swindon) of high-speed travel in that short time frame. A massive load in a short period and you also have to deal with all the heat that could be generated by doing that.
Well you could have robots that took out the dead batteries and put in some fresh ones. And then charge up the dead ones before the next train arrived.
I suppose things get easier with davesgr's fixed bar catenary - you can build some kind of "roof" into the support arrangements so running water is diverted to either side of the catenary bar, especially as with a bar, you don't have the problem of it all moving around - handy in tight clearances.
I think that would be a significant problem. You get maybe one or two minutes at a station?
You've got to deliver all the energy that a train's going to use over perhaps the next 40 miles (e.g. Reading to Swindon) of high-speed travel in that short time frame. A massive load in a short period and you also have to deal with all the heat that could be generated by doing that.
Well you already started charging them, when you applied your regenerative brakes to stop at the station.
There have been some recent breakthroughs in battery technology, which promise to give us a lithium-ion battery that can be recharged extremely quickly.
But I wouldn't be surprised if - appearance-wise apart - catenary is the most effective way of powering trains, simply because you're not lugging fuel or batteries around with you.
cybertect
It's grim up north (London)
Just fit the sides of the train with a huge gasket and borrow a few Dysons from Chippenham...
http://en.wikipedia.org/wiki/Atmospheric_railway
Crispy
The following psytrance is baṉned: All
Could be a goer.
I have a feeling there's plenty of clever professionals who have and still are puzzling this one out though. It'll be interesting to see how they do it.
You cannot charge up fuel cell batteries, you have to put more fuel (eg hydrogen and oxygen) into them.
From wikipedia:
davesgcr
Reading books
He is cagey cos he has done about 7 x 12 hour days 9(+ on call) helping to sort these things out + normal job
Can you all just believe that it can be done and be grateful that electric trains are the way forward
Most tunnels are wet by the way - its a question of engineering and maintenance........itsnot like there are permenant watefalls down the tunnel sides.
(first round on me when the first leccy rolls into Swansea - numbers limited though)
Can you all just believe that it can be done and be grateful that electric trains are the way forward
Most tunnels are wet by the way - its a question of engineering and maintenance........itsnot like there are permenant watefalls down the tunnel sides.
(first round on me when the first leccy rolls into Swansea - numbers limited though)
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