Track on bridges and viaducts

Discuss the prototype and how to model it.
David Knight
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Track on bridges and viaducts

Postby David Knight » Sat Dec 29, 2018 9:04 pm

A small question. I am about to do track on a viaduct for the first time and am unsure as to the positioning of checkrails. It will be bullhead rail so I assume the checkrails will be the same. How far ahead of the bridge do the checkrails need to start and do they go the full length? Apologies if my terminology is not correct. :oops:

Cheers,

David

Phil O
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Re: Track on bridges and viaducts

Postby Phil O » Sat Dec 29, 2018 9:28 pm

Hi David,

From memory, each viaduct was done differently, the aim of the check rails was to prevent derailed vehicles going over the side. Without knowing your preferred prototype and period, I can't be more specific, being a GW aficionado.

Phil

David Knight
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Re: Track on bridges and viaducts

Postby David Knight » Sat Dec 29, 2018 10:38 pm

In theory the track would be in southwest Scotland so G&SW, Caley territory originally then LMS but modelled in early BR days.

Cheers,

David

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grovenor-2685
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Re: Track on bridges and viaducts

Postby grovenor-2685 » Sun Dec 30, 2018 9:51 am

For interest GW/BR(W) practice can be seen here:
http://www.norgrove.me.uk/GWRtracknotes/R1777.pdf
http://www.norgrove.me.uk/GWRtracknotes/R4340a.pdf
http://www.norgrove.me.uk/GWRtracknotes/R4296A.pdf
http://www.norgrove.me.uk/GWRtracknotes/R4340b.pdf
http://www.norgrove.me.uk/GWRtracknotes/R4350.pdf
Other companies may do similar or different things, inside guard rails would be quite difficult on longitudinal timbers with bull head track so a lot depends on the viaduct construction.
Rgds

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Rod Cameron
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Re: Track on bridges and viaducts

Postby Rod Cameron » Sun Dec 30, 2018 12:14 pm

On the Ouse Valley viaduct we have found that the style of guard rails changes quite often, usually some form of FB rail (probably conductor rail) spiked in the four-foot, but at varying gauges, and sometimes some form of rail or bar attached to the outside of the running rail. (Our question would be why do they keep changing it - I'm not aware of any incidents that might have caused a review.)

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We're going for something like the first one.
Rod

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Martin Wynne
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Re: Track on bridges and viaducts

Postby Martin Wynne » Sun Dec 30, 2018 12:14 pm

Plain rail spiked to the sleepers for the guard rails on Chirk Viaduct in 1989:

Image

Starting well in advance of the viaduct in the facing direction, but finishing immediately at the trailing end.

Chirk Aqueduct on the left:

Image

Martin.
40 years developing Templot. And counting ...

David Knight
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Joined: Sun Jul 20, 2008 6:02 pm

Re: Track on bridges and viaducts

Postby David Knight » Sun Dec 30, 2018 2:45 pm

Thanks to all. I now have a sense of direction as to what I’m going to do. ;)

Cheers,

David

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Noel
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Re: Track on bridges and viaducts

Postby Noel » Sun Dec 30, 2018 3:16 pm

"Bridges for Modellers" shows viaducts without guard rails in a number of cases; https://www.railforums.co.uk/threads/extra-rails-over-bridges.117035/ may explain at least some of the reasons why, although some photos in the book suggest that the answer may be rather more complex. It may be that train speed and length of viaduct also affect the situation, although that is speculation on my part.
Noel

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grovenor-2685
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Re: Track on bridges and viaducts

Postby grovenor-2685 » Sun Dec 30, 2018 5:26 pm

One of the requirements of the HMRI was that bridges and viaducts should have substantial parapets a minimum of 12" above rail level and capable of restraining a derailed vehicle from falling off said bridge/viaduct. In the absence of such a parapet then guard rails were required, THe only place speed could come into it was in calculating the adequacy of a parapet.
Rgds


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