Chances are good that if you’re building a model railroad, you’ll want to include a bridge. After all, who doesn’t love a good bridge? I can’t speak for anyone else, but when I think of San Francisco, I think Golden Gate. When I think of Duluth, Minn., I think of the Aerial Lift Bridge (well actually, I think Bob Dylan, then Aerial Lift Bridge, but that’s beside the point.) The Millau Viaduct bridge in Southern France is one of the greatest achievements in engineering of this century! The list of great bridges, of course, goes on, but I digress. The point is this — bridges are cool. So too are bridges on model railroad layouts.
Bridges are more than signature superstructures, though. The humble, uncelebrated bridges of the world are myriad. Chances are good that you cross one on your commute without so much as thinking twice about it. And of course, who could forget the ever-essential yet oft-overlooked culvert, invisible to all but the eye actively seeking it?
If your layout is based on a prototype and requires a bridge, you will likely attempt to re-create the bridge present on the prototype to the best of your ability, whatever that bridge type may be, and rightfully so. If, however, you are freelancing and are wondering what bridge type would be appropriate for your location, era, or industry, or if you’re a modeler looking to better understand the many types of model rail bridges, then read on — this article is for you.
For most of the bridge types listed below, there are hybrid versions synthesizing one with another. For example, there are plate girder bridges with trestle supports allowing them to cross larger gaps than would otherwise be possible, or steel bridges with concrete supports, or bridges of any type really which must incorporate some moving element to allow for clearances which would not be possible without such features. We will start, though, with perhaps the most uncelebrated of all bridge types…
Culverts
Culverts are everywhere, particularly on rail lines, where it is estimated that there are approximately three culverts for every bridge. Rail lines are typically elevated from ground level, which causes drainage issues along the line. This makes them especially susceptible to flooding, which can cause catastrophic damage to roadbeds, quickly eroding away the earthen material beneath the rails and damaging the integrity of the tracks. Culverts are used as a remedy to this issue. This humble, easily ignored feature found on so many rail lines is certainly not as glamorous as a larger steel truss or multi-span plate girder bridges, but they are an essential infrastructural element nonetheless.
Culverts are relatively easy to model, and add prototype-accurate flavor to your layout with relatively minimal effort. Culverts come in many forms, from simple drainage pipes to wood or concrete box culverts, like the one seen above on a product photography diorama we use here at Model Railroader.
Wood bridges and trestles
The first bridges built for rail lines were typically constructed of wood, making bridges of this material appropriate for steam-era rail lines. By the mid-20th century, wooden bridges were becoming increasingly scarce along rail lines as they were phased out for bridges made of steel or iron. Wooden trestle bridges have proved to be particularly popular with steam-era modelers for their eye-catching appearance and the intricacy required to model them.
This wooden bridge, seen in the foreground of the above image at Whistle Creek on Model Railroader‘s HO Virginian Thin Branch layout, was outmoded by 1955, the year in which the layout is set.
Iron and steel truss bridges
As wood bridges and trestles were phased out in the mid-20th century, they were often replaced by bridges made with iron or steel. This more durable, more weather-resistant material introduced structures that would last longer than their predecessors while also requiring less maintenance. These bridges would be appropriate for late steam-era layouts and beyond.
This steel trestle bridge, at Skyridge on Model Railroader’s HO scale Milwaukee, Racine & Troy staff layout, was a favorite location of visitors and staff members alike. It frequently made for a dramatic, scenic location, as do many other bridges of comparable elevation.
Stone and concrete bridges
Stone bridges were the alternative to wooden structures in the early days of railroading, prior to the advent of bridges of iron or steel design. Stone, though, is a decidedly less pliable material than wood, and much heavier, making it a more difficult material to build with. Bridges made of stone were almost always constructed in the shape of an arch.
Stone bridges have proved to be incredibly durable, but the difficulty involved in their construction meant that few were made when compared to wooden bridges in the same era. Concrete bridges, however, offer similar benefits to stone bridges, but are far easier to construct. Stone bridges are appropriate for early steam-era layouts, while concrete bridges are well-suited for layouts set in the late steam era and beyond.
These concrete bridges, seen on Model Railroader’s HO scale Beer Line layout, showcase a couple of the many possible designs of concrete bridge one might encounter.
Plate girder bridges
Plate girder bridges are the most common form of bridges found on railroads today. These versatile bridges offer many benefits: They are inexpensive to produce, inexpensive and relatively easy to install, and inexpensive to maintain and replace. They are the preferred bridge type for smaller crossings, such as streets or small rivers.
This bridge, which spans across Illinois Route 251 on the N scale Milwaukee, Racine & Troy State Line layout, is a single span plate girder design.
Bascule, swing, and lift bridges
Bascule, swing, and lift bridges are the more mechanically interesting types of bridges. While massive trestle bridges are certainly impressive feats of engineering, bridges of the aforementioned variety require movement to accommodate for their surroundings. Bridges of this type can commonly be found near shipbuilders and other such ports that must accommodate large vessels that could not otherwise fit underneath them. Famous instances of these bridges can be found in Duluth, Minn., and in downtown Chicago, Ill. If your layout includes a ship yard, a shipbuilder, or even tall-masted sailboats, and you need to cross a waterway that could be used by these vessels, you’ll want to consider a bridge of this variety.
Bridges can be a difficult modeling task, but also a rewarding one, and depending on the region or industry you are modeling, an essential one, too. Hopefully, you have a better understanding of bridge types and where and when they might be used on your layout.
Looking to learn more about model railroad bridges? Check out The Model Railroader’s Guide to Bridges & Trestles by Jeff Wilson!
