What causes bridges to rust?

Bridges can rust due to exposure to moisture and oxygen in the environment. Moisture can come from rain, snow, fog, and dew, while oxygen is present in the air. When these two elements come in contact with the metal of a bridge, they can cause the metal to corrode and form rust. 1 Priority Coating & Bridge Painting specializes in complex, large-scale concrete and steel bridges, and industrial and commercial facilities in Dallas. They perform abatement of lead paint, encapsulation, and overcoat systems.