I guess the other question is what era do you model and what area? In the east many viaducts were done all in stone and are still in use today. In the west wood predominated though most of it has been replaced by concrete or steel on longer structures. Kits for all of the above exist. Good luck. J.R.
Have you looked at Grand Central Gems pre-built trestle bents? I think they make them in O, HO, and N scale in 3 different sizes for each. Once the bents are in place, the rest is scratch building to cut and install all of the cross beams and deck.
Have you checked with Black Bear trestles? They have everything you are looking for including the appropriate jig and all materials.
Skip:
The most important part of building a timber trestle bridge is a good "jig" for constructing the timber bents (posts, caps and transverse bracing). As can be seen in this photo the bents of my bridge are of different lengths. (OK it's outside, it "G" scale, but building a bridge in any scale is the same, just the materials change.)
After building the jig, I drew lines on the back of the jig to denote the different lengths required. On the straight sections of the bridge the stringer (timbers spanning the gap between bents) can be continuous length spanning the entire length. On curves just place the bents a little closer and make the stringers shorter, spanning single gaps. In my bridge I used nails and wood screws and it is concreted into the mountain at the end, so I have been delinquent in installing the longitudinal bracing. In the smaller scales you will need the longitudinal bracing for stability.
Tom Trigg
Check this guy out, he does build in HO also
This might help. there is a video avilible too
http://model-trains-video.com/e107_plugins/forum/forum_viewtopic.php?239
I think it would look very dramatic!!
ratled
Modeling the Klamath River area in HO on a proto-lanced sub of the SP “The State of Jefferson Line”
I have decided that building a scratchbuilt trestle would look better than having 4 bridges and a small section of built-up land all running together... (see picture below). Looking at it from left to right, the track will cross over a lower section of track with a dirt road running beside it, then a river, then a city road running off of the layout, then a spur from the yard. Then, it will go over a short section of 1/3 18"radius track (and I have no idea what to do there, other than to make a tunnel portal type of structure as seen in the picture), then go over another bridge over a double line below.
As you can (hopefully) see by the picture, that many bridges that close together does not look good, nor realistic...to me. I thought a long trestle may look better. Anybody know of any good trestle kits that would be that large? Do I buy 2 and combine? What about any other ideas???
Thanks again for all the help!!
Skip