Home > Encyclopedia of Science > Bridges

• Forces acting on a bridge
• Words to Know
• Beam bridges
• Cantilever bridges
• Caisson
• Arch bridges
• Suspension bridges
• Movable bridges

Bridges are structures that provide a means of crossing natural barriers, such as rivers, lakes, or gorges. Bridges are designed to carry railroad cars, motor vehicles, or pedestrians. Bridges also support pipes, troughs, or other conduits that transport materials, such as an oil pipeline or a water aqueduct.

Humans have been constructing bridges since ancient times. The earliest bridges were probably nothing more than felled trees used to cross rivers or ditches. As civilization advanced, artisans...