Okay, you’ve planned a great model railway layout and have constructed a table to neat the band, laid out the basics of your scenery and have come to the point where you’ve simply got to cross that bridge!
Building a model railroad bridge isn’t as hard as other tasks you might have to do, but it’s something you need to consider carefully if you want your layout to have the reality and dramatic appeal you’ve envisioned. I mean, think about it; isn’t the most climatic point in your railway’s journey the point at which it crosses that river gorge or canyon, proving themselves as wonders of modern engineering? Does your eye ever wander from the layout when the train approaches the bridges? I thought not. Perhaps we’ve been conditioned too much by the movies to expect a train derailment at precisely the point the train crosses a huge gorge, but the fact remains it is a dramatic set piece.
You actually seldom see a model train layout without some sort of bridge, whether it was constructed by the modeler or purchased as a pre-made piece. The various methods of getting a train on your layout include buying the ready-made bridge, constructing one from a plastic kit model, or constructing your own from scratch. The NMRA has the basic data on the various types of bridges and their construction available in their data sheets. Here we’ll focus on the last choice, as that is the one where the most craftsmanship comes into play.
Planning your layout is essential for success here. It’s a great deal easier to position your bridges while the layout is still in the planning or early construction stages. It’s easy to forget, for example to leave enough room on both sides of the bridge for the inevitable sloping embankments that lead to each side of the bridge. Had you already set this in stone, so to speak, the only option you have is to remake your bridge. Also remember to remove the roadbed nearing the bridge so you can lay the rails and ties directly on the bridge just like the real thing.
While there is no one prototypical railway bridge. Most lines preferred one style over another. You’ll need to consider this when planning, and do some research if you’re making a historical layout to see if they used wooden trestle-style bridge, a steel-arch bridge, a steel girder style, a steel fabricated bridge or a plate girder bridge. There are more styles than this, but these are some of the most common.
The wooden trestle is, in my mind, the most picturesque and dramatic of all the the aforementioned railway bridges. It’s a dying breed however, as modern railways don’t risk constructing trestle bridges out of wood anymore due to fire and maintenance concerns. But back in the day, wood was definitely the weapon of choice when it came to bridge construction.
While very pretty, the trestle bridge is by far the most tricky to install and get right. Each end of the bridge must be supported by abutments to hold back the ‘earth’ that supports the ends of the bridges. Also, each individual ‘bent’ of the wooden trestle bridge must be planted firmly in the earth (plaster ‘earth’) and this can be problematical if you’ve already set the scenery totally in place, another case for concurrent construction. Personally, I think the best way is to work both at the same time, thus ensuring a great fit and realistic scenery to boot.
Adding more detail to the scenery surrounding your bridge is easy at that point, and you can fill to your heart’s content. Just make sure the trestles are secure and level, or else you do risk the kind of derailment you see in the movies.
Another related point would be to test the viability of the bridge if at all possible before continuing on with too much more finish and detail work, as if there is an adjustment that needs to be made it’s easier to do it at this stage. Other styles of bridges in†mediums other than wood have their own particular needs, but the basics mentioned here would apply to all of these as well as far as in terms of support and planning.
Planning and constructing a model railway bridge from scratch is one of the more satisfying and rewarding projects in this hobby. You will always be able to point at the bridge with pride and claim it as your own. If you have the time and the inclination, don’ t hesitate to give it a try!