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Picture yourself down on all fours, as if you were about to crawl across a room.
If someone placed one of the following things—a feather, a cat, or an elephant—on your back, which one would break it? Obviously, it’s the elephant!
The design of a beam bridge is similar to you on all fours: a horizontal beam (your back) is supported at each end by piers, or vertical posts (your arms and legs). The beam, or girder, bridge is the simplest and least expensive type of bridge to build. Its design is perfect for crossing short distances.
