Trying to understand a bridge description

[Penrhos1920]

So a bridge that I'm going to model was described in an inspection survey dated 1905:

"with one span of 70'6 and 3 spans of 60'6 formed by steel plate girders with cross-girders, rail-bearers and floor plates on brick in cement piers and abutments; total length 109 yds."



By rail-bearers I presume it means sleepers? Or does it mean longitudinal timbers? With or without ballast?

 

[Martin Wynne]

@Penrhos1920

Hi,

Welcome to Templot Club.

"rail-bearers" means longitudinal timbers, usually called waybeams. The bridge construction will be something like this:

"brick in cement piers and abutments" means ordinary brickwork was used for them. "Brick-in-cement" should normally be hyphenated, i.e. in contradistinction to older traditional work using lime mortar. Portland cement was new in the 19th century:

https://en.wikipedia.org/wiki/Lime_mortar

cheers,

Martin.

 

[Phil O]

I would hazard a guess and say longitudinal timber bearers, if it was standard timbering, they would be on a traditional ballast base.

 

[Derek]

Hello Martin

I'm guessing that photo of the bridge is yours- you can always tell one of yours as you wait until the trains have gone. If so, could I possibly ask permission to download it for personal use, please?

For years I've wanted to build something but never could- time and space, also the M word. But that looks ripe for a very small diorama.

Interesting to see the welded BH rail to the left. I've never seen that before, although I've read you and others talking about it.

BTW if the OP doesn't mind me adding this to his question: is there any rule about whether to use longitudinal beams or transverse sleepers with ballast? From what I've seen length, height of the deck, speed of trains- nothing seems to have a definitive factor as to which method is chosen.

Thanks
Derek

 

[Phil O]

A lot will depend on the era that you intend to model, these days heavily used lines are being converted to ballast and sleepers as it distributes the loads better, the downside is that it makes the bridge inspection more difficult, as the ballast should ideally be removed first. There have been a few close shaves with regards bridges being on the verge of failure, due to poor inspections.

 

[Martin Wynne]

Hello Martin

I'm guessing that photo of the bridge is yours- you can always tell one of yours as you wait until the trains have gone. If so, could I possibly ask permission to download it for personal use, please?

@Derek

Hello Derek,

Sure, go ahead. Lichfield City 1990.

Here are a couple more. These are higher resolution versions:

cheers,

Martin.

 

[Derek]

Many thanks Martin

Just as a point of interest, the left two tracks over the bridge with the background is uncannily close to an artist impression of a station that was planned near me but never built. The usual thing- miles of embankment, then ran out of money...

NB the modern view of the station is very different with just the two inner tracks remaining and now disfigured by the overhead wires.

Thanks again
Derek