I have a couple of place on my layout that need a couple of simple bridges. I decided to make Pre-Cast Concrete type bridges. In thinking about how to do it, I came up with the following idea and have decided to use it.
Get some of these:
Remove the track, glue some sections of the track base together and add .125 x .125 square styrene strips to the sides, top and bottom.
Fill or cover any holes in the base, and paint. Also make two ends and glue on the base ends (2) to dam up the ends so water won't run out.
Glue on the track that was removed, but on the BOTTOM of the base sections.
And, make some bridge supports.
Set up the new bridge and connect it to the abutments of the solid ground and add the bridge center supports.
Ballast the track as you normally would.
Weather the bridge structure, paint the rails, add scenery around the area. Feeders could be added underneath on the bottom, but if you solder all rail joints and provide feeders close to the end of the bridge, it should be OK.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
Looks like a good idea.
Man! Those grades look STEEP!
The center bridge is the main line and sort of short. (less than a train length) The other two are for industrial switching with just a few cars.
EDIT ADDED
Part of it is an illusion too. Each change in track level is two inches. However, what you see is a set of grades that span a deeper level of the layout. They are in the neighborhood of 4%. Now I know that this is considered steep for a mainline RR, but this isn't a mainline RR. It is a branch. Plus, the plan came from MR, so how bad can it be?
And that brings up a pet peeve of mine. Who says you can't have steep grades if your equipment can handle them? I think everyone pays too much attention to what the NMRA has published in their standards. I know using them makes for a good running layout, but if you don't have all the room you need, who says you can't vary from them. Are the model RR police going to come after me if I deviate from them?
Sorry, I just had to rant a little about acceptable grades.
Bill
"Never try to teach a pig to sing. It wastes your time and annoys the pig"
alfadawg01 wrote:The problem with your design is that you have no beams to support the roadbed that the track lays in. Concrete has very little tensile strength, so bridge beams in real life are very deep and still contain plenty of steel reinforcing. Look at any highway or railroad bridge made of concrete (cast-in-place or precast) and you'll see what I mean. Add some square beams that are at least 4 or 5 feet square between each vertical pier and you'll be on your way to a more realistic looking bridge span.
As I see it, the beams are underneath, so you don't see them. However, you do bring up a good point about the size of any beams to be used. They would be showing to some extent when you look at the structure. And if they were painted a different color, would bring more variety to the scene.
IMO, to make this bridge better, I am going to add a couple of steel beams on the bottom, maybe set in just a bit from the square styrene strip. That would give the illusion that the beams are present. I'm not sure if I would make them a full five feet deep. Just something that "looks" good. After all, we modelers use a lot of selective compression in our modeling. Plus, the more supports that are used, the smaller the beams could be. The center supports shown are just two of four or more that will be actually used.
Thanks for your comments, because the long one did look a little spindly directly from the side. Adding some beams should correct that.
Enjoy.