viaduct

A viaduct is a long bridge-like structure built to carry a road or railway across a valley, ravine, gorge, low ground, or other routes below. It often has multiple arches, piers, or spans. Unlike a shorter bridge that crosses one clear gap, this kind of structure is usually longer and is used where the land is uneven or where several openings must be crossed in one stretch.

Although many people picture grand stone arches, especially in older European examples, viaducts can also be made of brick, steel, or concrete. The term itself was formed in the early 19th century as a partner to "aqueduct." An aqueduct carries water, while this structure carries a road or rail route. The comparison helps explain the word, even though the two structures are used for different purposes.

In the 19th and early 20th centuries, these structures became especially common with the growth of railways. Engineers needed ways to keep slopes gentle for heavy trains, and building high across valleys was often the best solution. Many famous examples have long rows of arches that give them a strong visual rhythm as well as practical support.

Today, modern designs vary a lot, but the word still often brings to mind a long, elevated route crossing open land with repeated supports below. So if you see a roadway or railway running high above a valley or above roads and tracks beneath it, you are likely looking at a viaduct.