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Author Topic: Great Western Main Line electrification - ongoing discussion  (Read 47507 times)
stuving
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« Reply #255 on: June 18, 2018, 04:59:58 pm »

My first reaction to this was "what do you expect with Swiss OLE? How may soggy underwater tunnels do they have?" But that's unfair - Furrer+Frey have many years' experience of fitting their kit all over Europe. In fact they are rather proud of its corrosion resistance, calling it "fit and forget" (though that phrase is usually unjustified hubris).

One place where corrosion is a specific problem with conductor rail (all systems, I suspect) is electrochemically between the conductor wire (copper alloy) and the beam (aluminium alloy). They squirt magic grease over this area to keep the air out, which doesn't sound to me like the height of high-tech. I can imagine that in this hyper-humid tunnel that could need to be inspected or re-done quite often.

But I hope the NR quote of:
Quote
"We are taking this opportunity to build on the modernisation work delivered in the tunnel during autumn 2016, including maintaining the new equipment and drainage system and removing redundant cables and telecoms equipment."

Network Rail said the maintenance of the new equipment mainly involves cleaning the conductor beam system.

It said it carries out maintenance work in the tunnel every year and that this will now form part of the annual process.
  doesn't really mean it will be closed for three weeks every year.
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Electric train
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« Reply #256 on: June 18, 2018, 08:18:05 pm »

Here's the article for those that are interested -

https://www.walesonline.co.uk/news/severn-tunnel-shut-three-weeks-14785503

Does anyone know if it's true?

Absolute tosh I'm afraid. Ever seen *aluminium* rust?


Its called cathodic reaction, aluminium and copper are not a good mix also aluminium and stainless steel will react.


The conductor beam is aluminium with the copper alloy contact wire inserted into (to all tense and purposes) a grove, stainless steel nuts n bolts are used to join beam section together and attach it to the registration arms.


An anti oxidising grease should be applied as the wire is placed into the "grove" however this is not a popular thing to do by the guys installing it, its very messy and slippery making the contact wire hard to handle,  not saying this the issue.


I suspect some corrosion has been noticed during maintainance, although the OLE is not energised or in use there is still a requirement for it to be inspected and maintained
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onthecushions
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« Reply #257 on: June 18, 2018, 10:16:17 pm »


Word has it that, since the week-end, the wires are now live to Wootton Basset.

OTC
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ellendune
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« Reply #258 on: June 18, 2018, 11:19:49 pm »

Here's the article for those that are interested -

https://www.walesonline.co.uk/news/severn-tunnel-shut-three-weeks-14785503

Does anyone know if it's true?

Absolute tosh I'm afraid. Ever seen *aluminium* rust?

It does't go brown in the way iron does, but it does oxidise in certain conditions. Unfortunately the corrosion products are white - very similar in colour to the metal so it is not as easy to spot at a quick glance. In normal conditions the oxide forms a protective coating on the surface, but in agressive conditions this is washed away exposing more metal. 

As ET points out the presence of other metals can make things worse.
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Bmblbzzz
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« Reply #259 on: June 19, 2018, 08:52:41 am »

Japanese motorcycles of the 1980s were notorious for forming white corrosion where steel bolts were used in aluminium engine casings. It's quite a common phenomenon.
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Four Track, Now!
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« Reply #260 on: June 19, 2018, 01:43:31 pm »

The problem is common, then. I'm sure some form of high-tech solution could be found using nuclear isotopes and a million pound machine with flashing lights, and a "ping" noise. But if smearing everything with loads from rendered down badgers does the trick, why not?
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Bmblbzzz
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« Reply #261 on: June 19, 2018, 01:54:40 pm »

YMustelidMV!
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Adelante_CCT
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« Reply #262 on: July 02, 2018, 09:16:21 pm »

I believe the Footbridge at Reading West was taken down over the weekend
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Jason
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« Reply #263 on: July 03, 2018, 06:27:39 am »

I believe the Footbridge at Reading West was taken down over the weekend

It was indeed gone yesterday morning.
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bobm
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« Reply #264 on: July 03, 2018, 10:54:43 am »

Reading West - July 2014



Reading West - July 2018





New footbridge under construction


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Adelante_CCT
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« Reply #265 on: July 03, 2018, 03:12:29 pm »

Quote
New footbridge under construction




I thought RBC and Network Rail hadn't agreed on a design/location yet?
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bobm
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« Reply #266 on: July 03, 2018, 03:27:54 pm »

I suspect this is a "temporary" structure which doesn't require permission.  However I understand there is a disgruntled householder who isn't happy that the base at one side is almost in his garden.
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YouKnowNothing
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« Reply #267 on: July 03, 2018, 04:12:51 pm »


for those of you that doubted that Network Rail would install something in a tunnel that could rust..... the minister has confirmed it-
I saw this on the BBC and thought you should see it:

Severn Tunnel electrification kit deteriorating, minister admits - http://www.bbc.co.uk/news/uk-wales-politics-44690614

Here's the article for those that are interested -

https://www.walesonline.co.uk/news/severn-tunnel-shut-three-weeks-14785503

Does anyone know if it's true?
Smiley
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paul7755
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« Reply #268 on: July 03, 2018, 05:06:07 pm »

I suspect this is a "temporary" structure which doesn't require permission.  However I understand there is a disgruntled householder who isn't happy that the base at one side is almost in his garden.
It could also just be a temporary structure to carry services (that were previously carried on the old footbridge), rather than an actual temporary footbridge.

Paul
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Tim
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« Reply #269 on: July 03, 2018, 05:40:15 pm »


It is an extremely harsh environment 

Made worse I expect by running diesel trains in the tunnel which chuck out acidic gases
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