I’m looking at creating a bridge that is curved, and thus a deck girder trestle. I understand that the bridge itself isn’t curved, but the girders are placed at angles to each other. Does anyone have a web site or point of reference to see how to most effectively do this, rule-of-thumb wise. Plus, and pics that anyone has of “curved” steel trestles or bridge would be much appreciated!!!
Thanks…
Shawnee:
Here’s a photo of the Deer Creek Viaduct on my Yuba River Sub–it’s a combination of two MicroEngineering tall viaduct kits, built on a 34" radius and a 2% down-grade. The ME kit includes instructions on how to ‘curve’ the bridge to almost any radius by shortening the girders on one side. It’s not difficult by setting up a template for the radius and using the template to assemble the girder deck.
Depending on the size rail you’re using, I’d reccommend either ME or Sinohars bridge track for the structure. I use Code 100, so I’m using the Sinohara, which has the guard rails built in.
Hope this helps.
Tom [:)]
So Tom - you trim the inside girder - the one on the inside stretch of the curve? That’s a good tip, better as I was planning just to match up the girders on the curve. How much did you trim the girders by?
I’m not actually getting the Micro-E tall viaduct, as this is a lower level bridge unit. I have a bunch of 30’ girders left over from an other project, and am hoping to string these together, and thus am looking for the tips on curving the trestle. I’m starting to wish that I had raised the level of my trackwork much more to accomodate those sweeping vista bridges!
Thanks.
I built the curved bridge, shown below, using Micro Engineering parts. The wider your curve radius, the easier the task, as you have to either shorten the girders on the inside of the curve or lengthen those on the outside (or a combination of both). I just took a closer look at mine, and can’t tell (or remember) which I did. [:-^] The radius is 34" and the bridge is also part of a 2.8% grade. I believe that the ME instructions include tips for making curved bridges.
Farther up the same hill, I built this bridge, also using ME parts, along with a couple of Atlas deck truss bridges. This one is on an “ess” bend, with a radius of about 48" at either end.
This is also a curved bridge, although not readily apparent from normal viewing angles:
I have one other bridge, also on a long “ess” bend, but it’s too long and too close the the front edge of the layout to fit in one picture. All of the bridges, by the way, are removeable as single units, which makes it easier to add scenery when I eventually get around to doing so. [swg]
Wayne
Shawnee–
First I drew the radius template I needed, then assembled each girder section, and marked on the inside girder how much needed to be clipped. Then after clipping and filing, I butted each section together with gap-filling CA.
Another method is to cut the curved deck you want out of 3/4" plywood or Homasote and trim the girder sections then attach it to the deck. I’ve never tried this method, but I’ve seen some solid-deck girder bridges using this method that are pretty darned good. However, I wanted an ‘open’ deck on my viaduct, so I built the ME bridge according to the instructions.
Tom
Hey guys, thank you…very helpful.
Dr. Wayne…super impressive bridges! Wow. I like the tall viaduct, but also the one with the large concrete piers too. The pic shot down on that concrete pier bridge is very cool. Where did you get the concrete abutments?
Tom - I think I may try your thought on just attaching the girders to a plywood curve section…it’s going to be a ballasted deck bridge anyway, and noone will be able to see up underneath. Seems simpler, maybe easier for me at this introductory stage in building such a curved bridge.
Thanks guys.
Changing the subject slightly, I had been told there was no prototype of a curved plate girder bridge. On the NRHS 4449/700 excursion I saw two of them on the old SP&S trackage along the Columbia. Not angled: curved.
Hal
Shawnee–
Sounds like a good idea to me, since your bridge will be ballasted deck. It’ll probably ease a lot of cutting and spacing (especially for the cross-braces on the girders). Frankly, I could have done the Deer Creek Viaduct that way, simply because after I installed it I realized that it was too tall to see the top of the deck, anyway, LOL! Oh well, live and learn–[:I]
Dr. Wayne–
On those bridges of yours, just one word—WOW!!! [bow]
Tom [:D]
This publication from kalmbach “Bridges and Trestles” has a detailed article on building a curved deck girder bridge
chuck
Nice trestles, good photos, Twhite: what kind of tender is that behind that locomotive??? it looks like an N scale thing, why would a large loco have such a small tender???
Tatans: It’s the prototype Vanderbuilt tender for the loco, which is a model of a Rio Grande 1400 2-10-2. That’s the way they arrived from ALCO in 1917. During WWII, some of the 1400’s were re-equipped with 12-wheel tenders from scrapped 2-8-8-2’s, but this lokie (#1408) kept her Vandy tender all her life. That’s why I ordered her from PSC–. One of the reasons for the shorty tender was that the locos spent most of their lives on a small part of the railroad, between Helper and Provo, UT, hauling freight and coal trains over Soldier Summit.
I think it looks kinda cute, myself [8D]
Tom [:D]
I’ll take a guess at this one - so that the loco and tender will fit on an existing turntable. I’ve always thought that a short tender on a big loco looks better than a long tender behind a small loco, and many times, a long tender behind a large loco.
There were some big prototype locos which had relatively small tenders, especially if they were built for a specific service where a short run was the norm.
Also, thanks to all for the kind remarks about the bridges. [;)] The concrete piers and abutments, as seen in the first two and last three photos, were cast in simple styrene moulds, using Durabond patching plaster.
Wayne