As railroads spread westward across the United States in the 19th century, engineers had to contend with uneven, loose and rugged terrain. Because an undermined rail could lead to a literal trainwreck, tracks had to be level and secure.

When setting tracks across wide valleys, wooden trestles were often built to keep the track on a level course high above the ground. Most trestles were meant to be temporary, allowing trains to cart in materials needed to create a solid fill beneath the tracks.

Trestles were also used as permanent installations in areas where water flow or flooding might make solid fills unsafe.

Temporary trestles mostly fell out of favor in the late 20th century, when newer technologies made it cheaper to construct a fill without a trestle.

Wooden, steel and concrete trestles still remain common on railroads across the country.



