The 6 Types of Bridges! - Teach Engineering At Home

We use bridges to safely travel all over our world. When trains, trucks, and cars needed to pass over large bodies of water or valleys, engineers stepped up to design the necessary bridges. Engineers have been designing bridges since ancient times when civilizations were being developed. 

I remember the excitement I felt as a kid when I drove over the Mackinac Bridge with my family. There was something magical about looking out the car window and seeing nothing but water and sky. If your kids get as excited as I was about bridges, you might have a future engineer on your hands! This article will explore the most common kinds of bridges we see today so you can talk to your kids about the wonders of bridges.

Beam bridges

The beam bridge was one of the first types of bridges designed by engineers. A vertical beam is supported by piers at each end. In its simplest form, a log laid over a river could be called a beam bridge if it is supported at each end. For more modern beam bridges we usually see multiple vertical piers that support the beam. Beam bridges distribute force by bending and compressing. 

Arch bridges

Arch bridges use a curved structure to support weight. Made popular by the Roman Empire, these bridges have been around for a long time. When heavy vehicles travel across the arch bridge, force is spread along the arches to the supporting pillars or abutments. The abutments hold the arches in place and ensure the bridge can support heavy vehicles. 

Arch bridges are not only efficient products of engineering, they’re also really lovely to look at! Some of the world’s most beautiful bridges are arch bridges. 

Suspension bridges

A suspension bridge uses vertical cables suspended from larger cables that run between towers and are anchored in abutments at each end to support weight. As heavy vehicles pass over the suspension bridge, weight is distributed by the cables to the towers. Because these bridges are often susceptible to strong winds, engineers make sure to design very heavy, strong decks. 

Cantilever bridges

Cantilevers are horizontal structures that are supported from one side only. If you stand up straight and extend both of your arms, you are making yourself into a cantilever bridge! Both arms act as cantilevers supported by your main body. 

Generally, a cantilever bridge has two sections that are attached to one side and joined at the center. Vertical loads are carried across the bridge by distributing force in the lower chords and compression in the lower ones. Towers then carry those forces to the foundation.

Truss bridges

Like the beam bridge, truss bridges also support weight by bending and compression. Truss bridges are identifiable by their signature triangle shapes. Engineers use this triangle shape to distribute force without damaging the internal structure of the bridge. Truss bridges require less materials than an arch or cantilever bridge and are more commonly found on today’s roads. 

Cable-stayed bridges

Cable-stayed bridges are similar to suspended bridges because they both use cables. The difference is that with cable-stayed bridges, the cables connect the deck to the end-to-end towers directly. This makes it easier for light traffic to cross and you’ll probably see some bikers on the bridge too! These bridges are low-cost and can be quickly constructed.

Final Thoughts

Bridges are an important part of our daily lives whether we realize it or not. Many of the products we use every day had to travel over bridges to make it to the stores where we buy them. Teaching your kids about bridges can be a lot of fun. Experiment by building bridges with blocks or popsicle sticks and watch your child’s curiosity grow!