scratchbuild or kitbashing a bridge?

[eastcoast]

Hey, a bridge 21 inches in length is VERY possible and WILL NOT detract from
scenery if done correctly. I built a kit bridge(s) using ATLAS and CORNERSTONE models. The strength of all my bridges comes from a 1/2 x 3 wood slat. The bridges are solid where they need to be, and look blended and compliment the scenery. The fact that 21" is possible with great strength is not as odd as 32" without supports.

[Anonymous]

There you go. I love working with plaster. I build sidewalks, roads, buildings, and retaining walls from it all the time. You can also carve cracks and stone work into it. The best tool I found so far is an eyeglass screw driver (the ones with the black blade and chrome handle). The driver can make fine lines and with a little twisting pressure also make wide lines. FRED

[Anonymous]

I think I've solved my problem. I bought some pipe insulation. It's foam used to wrap water pipes in cold areas. It's also dirt cheap. It comes in varying lengths and the stuff I got has a 3/4" inside diameter. It is also slit lengthwise allowing easy removal later. I simply cut it to length, poured in the modelling plaster and let nature take its course. One hint, run a piece of tape around the insulation so it doesn't spread open as you put the plaster in. It leaves a pebbly surface much like I had hoped for, making my bridge piers look rough-cast.

[Anonymous]

Thanks for your suggestions. It's nice to know I'm not alone out here in "neophyte land".

[Anonymous]

Concrete supports are easily made with with a piece of thin plastic tube (like the tube hobby knives come in) or such filled with casting plaster. After the plaster sets remove the plaster and use acrylic washes to color. You are going for the concrete piling look I assume, so the caps can also be cast with plaster in a form. Forms like this can be made from cerial box covered on the inside with plastic box tape. The tubes can be made that way too, but it's sometimes hard to get them round. Plaster is fun to work with and can be sanded, carved, and glued and is softer and easier to detail. It also takes on excellent colors with washes. One I use for concrete is coffee. It takes lots of coats to darken plaster so it's easy to control. FRED

[Anonymous]

bobbo...

I have painted carved balsa to look like poured footings using floquil "aged concrete". The water based paint raises the grain a little to give some good texture. I think the main thing to keep in mind is what sort of marks would the forms leave on the column, and would anything be done to modify it - most piers today are very smooth, even though they are cast on-site in a form.

Andrew

[Anonymous]

New problem... I intend to use wood dowelling as bridge supports. Any ideas how I can fini***he dowel to look like rough-cast concrete?
Thanks
bobbo

[Anonymous]

Actually, the Central Valley truss was the first thing I though about, but I didn't think it would span the entire gap. Now that you are able to reduce the span, I would recommend either the Central Valley single track truss or one of the Campbell trusses for 150 ft span. Campbell makes a single and a double track version. Be careful though, some truss kits do not have all the overhead clearance necessary for double stack trains. Fortunately, you wont have that problem in your era.

[Anonymous]

Wait! No one mentioned the Miami Valley Products bridge through truss kit? They offer redwood I-beams in a kit that works out to 24" or so, and some even longer, double track available... You need a hobby saw and gel CA or wood glue. [phone] or 1723 Lockbourne drive Cincinnati Oh, 45240. Also, the famous Central Valley bridge is pretty close to your size, and has the more prototypical spindly cross-braced beams... check a photo out here:
http://www.walthers.com/exec/productinfo/210-1902
or, go to Walthers and do an advanced search for Structures: HO scale: keyword:Bridge
and you can see the various Campbell, Micro Engineering, etc....
Of course, you can always get creative and kitbash any to shorter or longer than they come.
Dean

[Anonymous]

Gentlemen: I've slept on it, re-examined my options, re-read your advice, and have decided on a couple of things. The bridge would be a little too massive and may scenically over power the rest of the mini scene. Therefore, by adjusting the angle of the way the lower tracks go under the bridge, I could shorten the span by about 5"and still leave the bridge as the primary focus of the scene without completely dominating the other scenic details. The Plastruct with rivets items I would really like to try for a truss bridge. Can't wait to start on it! This project may have to wait 3 or 4 weeks to take though as though I have quite a bit of other priorities in the vein of weathering and laying mainline trackage on other areas. Will let you know how I make out.
Thank You! Being a "lone-wolf" modeler, it is good to talk to other people once in a while to bounce around some ideas and give and get feedback on how to approach various things in our hobby. That's why this web site is so cool!
Matt

[Anonymous]

Matt; There's a real good set of plans for a Steel deck bridge in this months (Feb) issue of Railroad Model Craftsman on page 60. Also there was an excellent article in the Feb issue of Model Railroader on page 68 for a real long steal deck bridge and that one is 18" long. I'm certain with a little modification on your part you could come up with something real nice. Ed's idea of the plastic materials is the best, that's what' I'd use. I've also seen some MR books on just bridges. The investments might be worth it....Walt

[Anonymous]

Matt:Is the reason for such a long span because of the scenic terrain, or because the upper track crosses the lower track[s] at a very shallow angle [ 20 deg. or less ]?
In real life, a RR bridge engineer would do everything possible to 'break up', or shorten such a span[s] to save cost, by trying to provide intermediate columns or supports adjacent to, or between, the lower tracks.In 1944, such supports would be steel or masonry.
regards/Mike

[Anonymous]

Matt,

Your bridge, 21 real inches long, would span about 150 ft in HO Scale. You would need a massive plate girder or a standard size truss for a span this long. What is the vertical separation between the tracks on the bridge and below the bridge? Based on what you have said, I recommend a truss. If the vertical separation is large, then I would use a deck truss, but if it is small then you could use a through truss. Is this a single track bridge? I would probably scratch build a truss from Plastruct (white) plastic shapes. They sell a plan for a through truss bridge that you could start with for your own plan. Central Valley also sells some 'Bridge girder parts' which are nice because they have rivet detail cast into them. I'll think about it some more and get back to you.

Good Luck - Ed

[Anonymous]

Any one have some advice for me? I need to install a mainline railroad bridge that crosses over another set of tracks. The bridge must be a minimum of 21 "real" inches long and be in HO scale. Also, since I model a free-lance version of the New York Central in 1944, it must look somewhat prototypically correct.I consider myself fairly decent at scratchbuilding with basswood and balsa but have no real experience with styrene. I haven't come across any blueprints that would work to guide me along. Kitbashing seems like the alternative I would like to take in this endeavor. What do you guys and gals think and can you recommend any decent kits for this purpose that cost a little less than a king's ransom it would be appreciated! Thanks.
Matt