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Long Span Model Railroad Bridges

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  • Member since
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Long Span Model Railroad Bridges
Posted by ROBERT PETRICK on Saturday, January 21, 2017 9:38 AM

There has been a lot of frantic activity recently across half a dozen or more threads regarding Bridges, Bridge Piers, Impressive Bridges, and the like. A little too unfocused for me, I think. And not a lot of thought just how such structures would fit into some as yet undetermined layout. Nevertheless . . .

I have designed and built several long span bridges. Here are photos of two, both N-Scale. One is 5 feet long without approaches (that works out to about 9 feet in HO) and the other is 14 feet long including approaches (about 26 feet in HO).

http://i1042.photobucket.com/albums/b430/rpetrick2002/Bridge-Model-05_zpsxkokkm9i.jpg

http://i1042.photobucket.com/albums/b430/rpetrick2002/Bridge-Model-06_zps7dpbblck.jpg

http://i1042.photobucket.com/albums/b430/rpetrick2002/Bridge-Model-03_zpssncfdp61.jpg

http://i1042.photobucket.com/albums/b430/rpetrick2002/RMP-Bridge-01_zpsgjxhagby.jpg

http://i1042.photobucket.com/albums/b430/rpetrick2002/RMP-Bridge-03_zpsudqdnfe5.jpg

LINK to SNSR Blog


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Posted by 7j43k on Saturday, January 21, 2017 10:25 AM

My, my, my.  What a treat to see these.

Thanks,

 

 

Ed

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Posted by MisterBeasley on Saturday, January 21, 2017 10:41 AM

Cool.  Keep us posted as the scenery develops.

It takes an iron man to play with a toy iron horse. 

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Posted by dknelson on Saturday, January 21, 2017 11:06 AM

Wonderful modeling.  A big bridge, used in a plausible context, is always an attention getter, particularly if the overall layout is large enough to serve as something more than just a stage for that one bridge.  

Although I have no engineering background whatever I have become something of a nut about bridges, and with that in mind here are some of the resources I have found interesting and worthwhile for a modeler to have in his or her library.  This is hardly a complete library on the subject, just what I have acquired over the years and can recommend should you find these books available.

The old classic, Paul Mallery's Bridge & Trestle Handbook, remains a very useful basic resource for the modeler.  I believe it is still in print, and has been since the late 1950s.  

Whether Kalmbach has kept their Model Railroader book "Model Railroad Bridges & Trestles" in print I do not know, but it was first issued in 1992 and my copy is the sixth printing from 2003.  The book is not BY Harold Russell but it might as well be as he is the dominant author.

British in origin but with plenty of useful content is Railway Bridge Construction - Some Recent Developments by F.A.W. Mann, published by Hutchinson International in 1972 (so take the phrase "some recent developments" with that in mind).  This is not for modelers but presumably for railroaders and bridge designers and consultants.  It is an overview, well illustrated, and not overly technical.  

Not entirely about bridges, but with plenty of bridge content and again well illustrated and not overly technical, is Modern Railroad Structures by Charles Disney and Robert Leggett, published by McGraw Hill in 1949.  It may well be a college text.

"FInal Report on Reconstruction Illinois Central Cairo Bridge Over the Ohio River" issued by the Modjeski & Masters engineering firm in 1953, this is a sort of "owner's manual" for the benefit of the IC all about the bridge they just bought and paid for (and the one that was removed as part of the project).  This is technical stuff, with tons of drawings, but is fascinating reading even for the layman.  I got my copy at a swap meet for the princely sum of $5.  I have no idea how many copies were issued in 1953.  The same bridge was the subject of a great article in the Winter 2012 issue of Classic Trains.

Lastly, a too little known resource of photos and surprisingly thorough information, is David Plowden's book "Bridges: The Spans of North America."  This is both an art book of wonderful black and white photos and Plowden's informed text about bridge design and aesthetics.  Plowden himself gave a wonderful talk about the photos and the book a few years back at Milwaukee's Grohmann Museum (devoted to themes of work and industry) and he donated the exhibited photos to the Museum afterwards.  Similarly Plowden just last night gave a talk at the Grohmann about his 178 extraordinary photos of the steel industry which were on exhibit (his largest exhibit ever he said) and he similarly donated all of those to the Grohmann Museum, which has also published a fine catalog of the exhibit.  Both the bridge and the steel industry photos have plenty of content to interest a model railroader or railfan.

Dave Nelson

 

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  • From: Shenandoah Valley
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Posted by BigDaddy on Saturday, January 21, 2017 11:11 AM

What is the trick in establishing the base height so the piers, of various heights in your pic, are neither dangling from the bridge nor pushing the bridge up higher than the adjacent pier?

Henry

COB Potomac & Northern

Shenandoah Valley

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Posted by floridaflyer on Saturday, January 21, 2017 11:26 AM

I'm guessing all the piers are the same height, and the scenery is built up around the ones that appear shorter.

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Posted by mbinsewi on Saturday, January 21, 2017 12:48 PM

The base height is what ever the depth of the ravine/river/valley or gorge to the elevation of the road bed, and the bridge that is required to cross such land features.

Not too long ago, someone else on here was building a bridge to replicate one out West, where the grade was a constant rise as it crossed the river and the valley below.  It actually went up hill, so the top of each pier was at a different elevation.

Kind of like running a string line from the road bed on one side, to the road bed on the other.  The piers would match the string line.

Mike.

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Posted by ROBERT PETRICK on Saturday, January 21, 2017 2:14 PM

floridaflyer

I'm guessing all the piers are the same height, and the scenery is built up around the ones that appear shorter. 

Yes. In the top photo, the three piers of the main span are the same height. The plywood deck of the benchwork under that section is flat and level. The middle pier is in deep water, the left pier is just on the shore and barely getting its feet wet, and the right pier is up to its waist in alluvial deposits forming the shoreline.

The piers for the approach spans up on the bank are shorter. The plywood deck in those locations is about three inches higher than the middle section.

To answer BigDaddy's question, gravity also plays a part. The piers are firmly screwed into the plywood deck and the bridge rests on them more or less like any other bridge. The whole shebang only weighs about 10 or 15 pounds, and that isn't  a whole lot in the scheme of things, but it is enough for gravity to take a hold of.

Robert

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Posted by NWP SWP on Saturday, January 21, 2017 2:36 PM

Since you are experienced in the contruction of large model railroad bridges, what tips would you have for one who has not done any scratch building?

By the way, nice bridge!

http://i1042.photobucket.com/albums/b430/rpetrick2002/Bridge-Model-05_zpsxkokkm9i.jpg

Steve

If everything seems under control, you're not going fast enough!

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Posted by ROBERT PETRICK on Wednesday, January 25, 2017 7:22 AM

MisterBeasley

Cool.  Keep us posted as the scenery develops.

For the first bridge the scenery has been fully developed. It was featured as part of a layout tour at the NMRA Convention in Atlanta 2013. Here's a photo taken from the LDSIG Facebook page. I don't know who took the photo. If I did, I'd certainly give him or her credit. I'd also ask if higher resolution photos were available.

http://i1042.photobucket.com/albums/b430/rpetrick2002/LDSIG-Bridge_zpswmysnxlj.jpg

And here are a couple of photos from the other side.

http://i1042.photobucket.com/albums/b430/rpetrick2002/RMP-Bridge-05_zpsfozsazvr.jpg

http://i1042.photobucket.com/albums/b430/rpetrick2002/RMP-Bridge-04_zpsl2sn7qfe.jpg

 

 

LINK to SNSR Blog


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Posted by -matthew on Wednesday, January 25, 2017 7:38 AM

This is fantastic!  Regarding the boat, was that a kit or scratchbuilt?  

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Posted by NVSRR on Wednesday, January 25, 2017 7:44 AM

BigDaddy

What is the trick in establishing the base height so the piers, of various heights in your pic, are neither dangling from the bridge nor pushing the bridge up higher than the adjacent pier?

 

The easiest way is to set the abutment with the road bed.   Cut your piers to height.  Put them in place but not secure them.  Built the bridge and put it in.  Put shims if needed under the piers.  Then secure piers when everything is in place and level.    Then do the scenery work. 

Shane

A pessimist sees a dark tunnel

An optimist sees the light at the end of the tunnel

A realist sees a frieght train

An engineer sees three idiots standing on the tracks stairing blankly in space

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