Bridge Help...... Please!

[Anonymous]

hey guys, hows it goin? not to good here. im in the process of installing my main line bridges and abutments. the problem is that i cant seem to get both ends level. im useing 4" of extruded foam for my sub road bed. im useing a 10" level, and a string line. the level shows good, but the string line shows its off. i have never installed bridges and abutments before, so if anyone has any ideas or information, please let me know. also, does anyone know of a picture of how a properly installed abutment and bridge, i would like to see what im supposed to have when im finished. thanks for all your help.

steve[:)]

[JCasey]

Hi Steve,
It sounds to me like your level isn't covering enough real estate. Try a 24" level if you have one or can borrow one. As far as pictures of bridges and abutments, I found a lot of pictures on www.railimages.com that helped me. Hope this helps!
John

[mls1621]

Steve,

Are the abutments free standing or are do they mount to the foam at each end of the bridge.

If they mount to the foam, try this. Install the bridge using your track to support it at each end. Then mount the abutments under it by gluing them to the styrofoam wall at each side of the bridge. By having the bridge in place, you can apply glue to the backs of the abutments and shim them to the bottom of the bridge.

Then all you have to do is use plaster or sculptamold to fill in the space under the abutments.

I hope this is helpful, Steve.

[Anonymous]

Steve:

Sounds as if you have the bridge level but the layout isnt. Check to see if the layout is level. Once you ave done that installing the abutments shouldn't be a problem.

Randy

[dand200]

Another thing to consider Steve - What is your string line attached too? Your anchors for the ends of the string may not be level if you mounted them to the foam. Foam is a great material to use for scenery but it can't be trusted to hold a straight line by itself after being mounted and may need to be planed and leveled after is sets up. Good luck.

[cacole]

Which way is it not level, sideways or lengthwise? I assume you mean lengthwise, since you're using string. There are many examples of real bridges that are on an incline, so it does't need to be level to be realistic.

[jfugate]

Having installed many bridges on my HO Siskiyou Line, I recommend building the roadbed and track right through the scene as if the bridge was not even going to be there (well, not quite ... put the roadbed risers approximately where you want the abutments to be).



Then I lay the track on the roadbed like normal. This way all the track alignment is as it should be along the route.

When I am ready to do the bridge, I come back and do a pencil tracing of the rails so I know the precise alignment of the track (especially useful for curved trestles). Tape together as many pieces of typing paper as you need, lay it over the track where the bridge will go, then run a soft lead pencil back and forth along the railheads on the paper to make their location visible on the paper.

From this tracing, I build the bridge to match, complete with rails hanging off the end. Once the bridge is ready, I go to the site on the layout and cut the rails and remove the track. Next I cut the roadbed and remove it.

Then I carefully set the bridge in place, mark and trim the rails to fit, and slide some railjoiners all the way onto the rails. Generally, the bridge just drops into place, no muss no fuss. Slide the railjoiners to connect with the adjoining rail, add abutement details, scenery, and you're in business.

BTW, I will be covering this entire process on camera in video 4 of the upcoming how-to series based on what I do on my HO Siskiyou Line. Follow the link on my web site (in my signature) for more info.

[Anonymous]

Another bridge question ? Did prototype railroads install st raight girder bridges in curves?

[cwclark]

to do a girder you are going to have to do what jfugate suggests...take the paper and trace the rails while a bridgeless section of curved track is in place..then lay the paper down on a table and take the sections of girder and try to get the best fit from them around the curve..there will be angles in the girder ends where they join together with gaps in them when you lay them end for end..cut the girder sections to the best fit possible...once you "angle the girders to the best fit you can, build the underdecking of the girder, once the under deck is complete and the girders are glued in place, glue styrene sheet plastic in the gaps where the angles are located in the girders to fit the curve in the track...kalmbach has a book called "Bridges and Trestles" that explain how to build deck girders in a curve..they will not be straight but will angle at the ends of each girder section to fit to the shape of the curve...by the way..j fugate is an excellent modeler... he's one of those guys you want to listen to in this hobby....Chuck

[Anonymous]

MR has had multiple articles over the years showing how to model various prototype bridges. They also publish a book, "Model Railroad Bridges and Trestles," that provides answers to the questions you ask. I bought one when it was first published and have used it extensively as the bridges were being built for the layout.

Steam is king.

Tom

[dknelson]

The late Paul Mallery bridge book is an oldy but a goody and is full of useful data and drawings.
Except for some highway bridges, steel girder bridges are not curved. If the track needs to curve where the bridge is, they build the bridge wider and the track curves on a straight bridge -- sometimes a sequence of straight girder bridges at slight angles to each other.
As to the level -- lately I have seen these laser levels that carpenter contractors use alot be available at consumer friendly prices. But I do agree with the prior poster about the floor possibly being the culprit -- that tricked me up more than once.
Dave Nelson