viaduct

A viaduct is a long bridge that carries a road or railroad over a deep valley or other obstacle. It's usually a series of arches that support the weight of traffic.

In everyday life, people often talk about viaducts when they're traveling by car or train and notice one in their path. They might say "We just drove over the viaduct" or "The train is going to cross the viaduct next". Engineers and architects are also interested in viaducts because they need to design them to be strong enough to hold heavy traffic and safe for people to use. Some famous cities have iconic viaducts that are part of their landmarks, like the San Francisco Bay Area's Dumbarton Bridge or London's Hungerford Bridge.