Installing Culverts and short trestles

[Anonymous]

Allen,

The nice thing about modeling a small culvert is that you don't have to remove any roadbed. The headwall is usually more than eight feet from the centerline of the track so you can just put the headwall in and scenic around it. Remember to make the headwall wide enough to account for the wrap around fill cone on each side. Many situations can be handled by only installing the near side headwall because the far side headwall would not be visible. If you use small culverts they would be spaced closer together. Make sure the drainage pattern around the scene fits and that the water appears to be flowing downhill.

Trestles are often used where the existing soil is poor and the engineering department has determined that a trestle is less expensive than removing the poor soil and replacing it with good soil. Such situations exist in swampy areas. In this case you will have a series of short uniform spans (ten to twenty feet each) with a longer relief span of fifty to a hundred feet every so often for a channel to flow across the track centerline. Many trestles of this kind are built without refuges since an employee could just jump off into the mud if a train came along. Other trestles are build in urban areas where the right-of-way (R/W) costs would be too expensive to build an earth fill wide enough to support the track. Retaining walls will also be used in that situation to reduce the width of the roadbed at normal ground level. In another situation, during the construction of the transcontinental railroad, a trestle was built and then earth was brought to the site and dumped between the rails and the fill was created later.

The ten to twenty foot spans described above would be built of timber stringers on timber pile bents with a steel beam or girder span for the longer spans. One thing to note, as the height of the rail above normal ground increases, so does the span. The reason for this is because as the trestle height increases, the cost of building the pier supports goes up substantially. By making the spans longer, fewer pier supports are needed and the result is a lower initial construction cost to the railrooad.

When building any kind of trestle or bridge, take special care to model the abutments and girder ends properly. I particularly like the bridge shoes sold in packages of four produced by Micro Engineering, Inc.

Good Luck - Ed

[orsonroy]

I'm modeling the midwest, and the tracks are lousy with little trestles. So far, I've only built one, but I laid the track first and build the trestle under it. I didn't figure that itd be worth the time and hassle of laying the track, building the trestle at the workbench, and tryint to cut and jam it into place. Besides, trestles aren't the hardest things in the world to scratchbuild, so long as you've got a decent supply of prestained basswood lying around.

[Anonymous]

Thanks,
The depth above was probably what I should have asked. Luckily I haven't attached the track to the roadbed or slapped some ground down. (Waiting on track orders) I might just try to fake the placement by leaving the roadbed and insert a false front below the roadbed.
By trestles I really meant a culvert type situation that wouldn't have the necessary depth and might even span a larger width, but be composed of timbers.

Allen

[Anonymous]

Allen,

Culverts are normally installed with four feet or more cover above the culvert to the bottom of the ties. This is done to distribute the weight of the axles over the culvert. Trestles have so many more situations, I would need some information before providing any guidance. Culverts are easily modeled with a piece of plastic to represent the headwall and a short section of tubing projecting outward. Color the tubing and plastic headwall medium tan for concrete. Paint the inside of the tube black and add a tiny amount of simulated water dripping from the tube.

Good Luck - Ed

[Anonymous]

Anyone have any tips on installing these little scenery items. I'm building an HO layout, and have identified where I need these items. However, I could use some tips. They aren't quite the same as bridges.

Allen