what length bridge spans ?

[guest311]

Hi all,

I'm looking for some views on how long to make the spans on a curved bridge / viaduct [think Findhorn viaduct on the Highland Main Line between Perth and Inverness]

I'm going to use the Ratio stone piers, with arches either end, and was intending to use the Peco truss bridge sides with the sloped ends removed to give a square end to each panel.

like that they are just short of  the length of a class 47, and when placed on top of a couple of piers, the piers look too close together.

I'm thinking along the lines of adding a couple of bays each end of each span, which will work out at about one and a half class 47s per span.

is this a reasonable length for a span, and does the method sound ok ?

thanks in advance for any suggestions or comments

cheers

alan

[edwin_m]

On a quick Google Image search the real Findhorn Viaduct has piers at about 130ft centres (one of the pics shows a train of Mk1 coaches on it and the piers are almost exactly two coach lengths apart).  So yes it looks as if you could get away with a slightly longer span.  For it to look structurally sensible you should try to keep the same ratio of span to depth, which based on the highly accurate ruler-on-the-screen technique is about 1:7 at Findhorn. 

[guest311]

many thanks for that, Edwin.

I'll bodge carry out a test build extending a bridge side by two panels each end, and see how that looks on top of a couple of piers.

I think if I went for 1:7 span to height, then I'd be cutting the bridge panels down,

the idea is to have the bridge on the upper level, at about eyelevel, so I'm hoping that will help with the lower piers, while still appearing 'dramatic'.

looks like I may need to investigate increasing the height of the piers.

cheers

alan

[PostModN66]

How about trying OO scale trusses?

Cheers   Jon   

[Newportnobby]

How about trying OO scale trusses?

Cheers   Jon   

I did try them, but they cut into my parts too much