A significant moment in your model railroading journey is when you start thinking about your layout as more than just pieces of track on a level surface.
We previously covered how to build realistic hills and mountains for your layout. And while that allows for elements like tunnels, it also creates space for you to raise the height of your tracks, allowing for bridges spanning roads, valleys, rivers, and even the same railroad!
Just like with any aspect of railroading, there are plenty of different bridge types to choose from. In this article, we’re going to go through some of the most popular styles, their uses, and the best locations to use them in on your layout!
Viaducts & Deck Arch Bridges
Typically found in Europe and on older east coast railroads, viaducts and Deck Arch bridges can be traced back to the aqueducts of the ancient Roman Empire. They are some of the strongest and most heavily built bridges in use today, and are distinctive in appearance thanks to their dramatic multi-arch design. These can typically be found spanning valleys and rivers and offer a majestic addition to any landscape.
US rail viaducts were often built from locally sourced stone in the early railroading era. In the 20th century however, some railroads such as the Lackawanna switched to cast concrete, which was cheaper to construct, but more prone to erosion. Despite this, many stone and concrete viaducts remain in use today, with even America’s fastest high speed railroad, the Northeast Corridor, continuing to rely on legacy stone viaducts in several locations.
The trestle is another one of the oldest types of bridges used by North American railroads. As railroads expanded west during the pioneer era, it was found to be easier and more cost effective to utilize the abundance of wood found across the nation to construct quick but strong rail bridges, rather than continue to build elaborate stone structures as found on the early east coast railroads.
Trestles could be built to cross just about every type of gap, from small streams and swamps, to massive valleys and canyons. Early trestles were built entirely out of wood, with closely spaced frames held together by supporting beams. As trains became heavier, and technology developed though, many railroads switched to steel trestles. These were built to essentially the same design, but included the added benefits of superior strength and longevity. Today there are still many examples of wood trestles in operation across North America, and steel trestles continue to be produced.
Plate Girder Bridges
Girder bridges are among the most mundane bridge types, but they serve an important purpose. They may not feature majestic arches or intricate latticework, but they are with little doubt the most common bridge type found across the North American rail system.
Typically used to span roads, highways, and sometimes other railroads, girder bridges are composed of a flat deck supported by parallel metal beams (or girders) which rest on a concrete, stone, or brick abutment on each end. Typically girder bridges will feature cast metal siding both for added structural integrity and to provide protection for those crossing the bridge. The simplicity of their design makes them a strong and cost effective option for shorter crossings on real-life railroads.
Although they can occasionally be found in other roles, truss bridges are synonymous with railroads. First patented in 1848, the Warren Truss is the most common subdesign used in railroad construction. The design consists of longitudinal members joined together by angled cross-members, and is usually constructed out of steel or iron. Truss bridges are typically built with the majority of their construction above-deck, with trains traveling through the framework, however some are built with an inverted design, with the framework underneath the rail deck. These are known as Deck Truss bridges.
Truss bridges can again be found across North America as well as elsewhere in the world, and can usually be found at river crossings. Due to their below-deck construction, Deck Truss bridges are typically only used in locations where the track height is significantly higher than the water level.
Other Bridge Types
Although the above four types are the most common, there are other bridge types with less prevalence that can nevertheless be found in the North American rail system. Some of these include steel arch bridges, which are derived from the basic design of deck arch bridges, reinforced concrete bridges, and even covered bridges on some New England lines!
Adding a Bridge to Your Layout
Having an impressive looking bridge is excellent, but for it to make sense on your layout, you need to consider how your trains will reach it!
There are two commonly used options for this:
- You can bring the track up to your bridge height by using Woodland Scenics Risers. Once installed, you can create a natural looking bank on each side of your roadbed using the same methods as you would to build a mountain. This is a great option for giving your operators an unobstructed view of your trains as they ascend over your landscape or city.
- You can carve out from under your trackbed height to create a valley, gulch, or manmade highway cut. For this method to work, we suggest building your railroad on a layer of insulation foam on top of your board, rather than directly on a wooden baseboard, as this will allow you to cut and mold the landscape and terrain height around your tracks to your liking.
Show Off Your Work!
Whether you’ve built your bridges from scratch or used one of our model bridge kits, we want to see what you’ve come up with! Tag us on Instagram so we can see your pictures of your bridge scenes, or send us your photos on Facebook!