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How common is this?


pH

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Apologies for the quality of the picture - it was a 'grab shot' as a train was running into the platform. It's on the Barcelona Metro.

How common is this for overhead power pickup? It appears to be a rigid rail. (Overhead third rail? e14505.gif

 

post-1771-0-11985000-1372373088.jpg

 

The train pantographs seemed quite normal.

 

 

 

 

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Is it to reduce headroom requirements?  All the cable type overhead that I've seem seems to require quite an elaborate and high support structure above the pick-up wires which I can see being awkward in underground applications.  To my shame (as a former regular traveller with an interest in railways) I can't remember what the Tyne & Wear Metro uses in its tunnelled sections.

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The system was used in Budapest for the original (1896) subway because of the low headroom (2.5 metres), the cars resembled a tramcar body mounted on a bogie well wagon. The pickups were similar to those used on the Snaefell Railway but mounted on the frames instead of the roof. A similar arrangement was used in the Hudson River tunnels but this was more of a third rail mounted on the roof of the tunnel to avoid problems with water seepage.

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The correct term is conductor beam.  It is used in areas of severely restricted headroom where speeds are low. This is used where the upward pressure of the pantograph would push a conventional wire up and compromise the elecrical clearance. There is some installed on Thameslink. The Trowse swing bridge was a special case: Movable conductors were required and this was not practical with conventional wires under tension.

 

The normal practice where clearance is restricted is to use twin contact wire supported on single glass fibre arms.

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The Thameslink installation includes the underground platfoms at St Pancras.  Crossrail will be using it and I believe it may also be fitted in the Severn Tunnel. 

 

I would be suprised about Crossrail needing it - the tunnels being new build and having sufficent headroom. On the other hand the refurbished Cannaught tunnel under the docks might need it.

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I would be suprised about Crossrail needing it - the tunnels being new build and having sufficent headroom. On the other hand the refurbished Cannaught tunnel under the docks might need it.

 

Unfortunately Crossrail is being engineered to a price and I can't see there being sufficient room for conventional catenary.  It's a hobby horse of mine, but I think it's a shame the tunnels weren't bored big enough for a bigger loading gauge such that there would be capacity to run double deck stock should traffic levels demand in the future.

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Unfortunately Crossrail is being engineered to a price and I can't see there being sufficient room for conventional catenary.  It's a hobby horse of mine, but I think it's a shame the tunnels weren't bored big enough for a bigger loading gauge such that there would be capacity to run double deck stock should traffic levels demand in the future.

I believe the DfT have confirmed that 'GB' size continental stock could in theory fit through the new Crossrail tunnels if platforms/catenary were suitably modified, but there's reason to think that will ever happen - the longer dwell times of such rolling stock, especially a design needing to cope with our high platform heights, would reduce the capacity of the line for minimal extra room in each carriage.

 

With no prospect of the GWML, GEML or Connaught tunnel being cleared for such trains it really isn't an issue.

 

Chris

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