Plate girder bridges

[Kris]

First the background.

I'm looking at constructing a bridge to carry a road across a single track line. In most instances this would have been more likely to have been a stone / brick built structure, however for the situation that this is to be planted in I feel that the girder bridge is a better and more suitable solution.

 

Now it's time for the possibly silly question...

Obviously there is a maximum length of the span but is there a minimum length?

 

And for a second question (maybe a more sensible one)

Are the plates on the side a standard size? i.e. Width and height. If so what is this?

 

Thanks in advance for any answers

[28XX]

There is no minimum span, or standard dimensions. The depth of the girders is determined by the span. The plates on the sides are not the main structural component, it is the beams under the road (in your case) which do most of the work.

 

I would strongly advise that you study a prototype, there are loads left in original condition, even Google Earth, if you can't travel, will be a great help. For realism, model what is (or was) actually there, not what you expect to see.

 

Edit: Pic added for inspiration. The A4538 crossing the Birmingham - Bristol main line.

[Kris]

Thanks for the reply. I shall have a look about to see what can be found.

[Baby Deltic]

Ratio do plate girders in packs, which you can use to make a bridge of any size with any depth of girders.

 

[Captain Kernow]

Here's one of my favourite girder bridges, just to the south of Honeybourne West Loop Jct on the former Cheltenham to Stratford main line, looking south. Honeybourne West Loop signalbox used to stand immediately beyond this bridge on the left hand side. I've got more photos of the detail of this bridge, both from track level and the road above, if you are interested, Kris.

 

 

Here is the girder bridge on Callow Lane, prior to painting:

 

 

My thread on building a small girder bridge:

http://www.rmweb.co.uk/community/index.php/topic/9322-building-the-rat-hole/page__p__81576__hl__%2Brat+%2Bhole__fromsearch__1#entry81576

 

 

 

(Nice photo of bridge and layout, btw Baby Deltic - is this the new one?)

[Galtee More]

An excellent source of both reference and inspiration is Bridges for Modellers by Les Wood (LV Wood). It was published a few years ago now by, I think, OPC (but I may be wrong on that one. If you can't locate a copy, your local public library should be able to obtain one for you.

[Kris]

Thanks for the suggestion B D. Unfortunately I think these are only 4mm so are to large for my use (2mm) otherwise I may well have gone down this route. They defiantly look a lot better than the ones produced by peco.

 

Tim

Thanks for the offer of photo's. That does look like a nice bridge but it's a little to large for my purposes.

 

G M I might look at picking that book up in the future, it seems to be obtainable second hand reasonably readily. I suspect that the bridge will be built before the book would arrive though.

 

[jamie92208]

I'm in the process of constructing a large multi span plate girder bridge on my layout and fortuantely managed to get the original construction drawings from the county council, as it still carries a road. In general the whole thing seems to have been made of 1/2" plate in various sizes. The depth of the web is determined by the lenthg of the span and mine had spans of about 70' and the plates were 6' deep. The top and bottom plates were 2' wide with only 2 layers at the ends but up to 7 layers in the centre of the span ao that the base and top got thicker in the centre and thinner at the sides. If I can manage to resize a pdf I'll try and post one of the drawings of the main girders which shows everything.

 

Cheers

 

Jamie

[Kris]

I think I have found a bridge of about the right size for me.

 

Not the best picture in the world. The train was moving and I wasn't particularly taking photos of the bridge. Unusually the girders on the side shown are significantly longer than the ones one the other side (2 or 3 times as long) Google streetview link

 

 

 

 

[Rugd1022]

To add to the good Captain's lovely shot at Honeybourne, here's one further south on the Stratford-Cheltenham line at Broadway, taken yesterday. There are quite a few of this design between here and Cheltenham

 

Nidge

[craigwelsh]

An excellent source of both reference and inspiration is Bridges for Modellers by Les Wood (LV Wood). It was published a few years ago now by, I think, OPC (but I may be wrong on that one. If you can't locate a copy, your local public library should be able to obtain one for you.

Yes it is by OPC and an excellent record, I got my copy at S4 North last year for £4.

http://openlibrary.org/books/OL11662208M/Bridges_for_Modellers

[Fat Controller]

This report from the RAIB about a derailment following the failure of a plate girder bridge may contain some material of interest:-

http://www.raib.gov.uk/cms_resources.cfm?file=/100203_R022010_Stewarton.pdf

[Glorious NSE]

There is no minimum span, or standard dimensions. The depth of the girders is determined by the span.

 

Presume also the expected load is a variable?

 

An illustration - the Santa Fe has some very deep plate girders on some of it's river bridge spans, dictated presumably by the combination of length and expected weight of trains crossing - compare with the shallower girder for the shorter approach span at right: http://railpictures.net/viewphoto.php?id=258896&nseq=2

[Kris]

This report from the RAIB about a derailment following the failure of a plate girder bridge may contain some material of interest:-

http://www.raib.gov....0_Stewarton.pdf

 

 

That makes some interesting reading! Good diagrams in there.

 

 

[Captain Kernow]

Kris, if you can find a book with photos of the old Fairford branch in it, there were some very narrow road-over-rail girder bridges on that line.

[Kris]

Kris, if you can find a book with photos of the old Fairford branch in it, there were some very narrow road-over-rail girder bridges on that line.

 

Thanks for that suggestion. I'll keep my eyes open.

 

This bridge is now well on it's way to being finished now. Hopefully there will be an update on Avonwick blog thingy later.

[Kris]

Thanks for everyones help with this question. I have now built much of this bridge (abutments and weathering still needed) It can be seen here.

[Rugd1022]

Thanks for that suggestion. I'll keep my eyes open.

 

This bridge is now well on it's way to being finished now. Hopefully there will be an update on Avonwick blog thingy later.

 

Kris / CK,

 

You should be able to find some photos in here... http://www.martin.loader.btinternet.co.uk/Fairford_Branch.htm

 

HTH,

 

Nidge

[Kris]

Thanks for the link Nidge. Some nice little bridges to be found in there!