Are piles considered part of a bridge's substructure?

Piles are indeed considered part of a bridge's substructure. The substructure of a bridge refers to the components that support the superstructure, which includes the beams, girders, and deck. Piles serve as deep foundation elements that transfer the load of the bridge superstructure down to the soil or bedrock beneath. This load-bearing function is critical for the stability and safety of the bridge.

In general, the substructure includes elements such as footings, piers, and abutments. Piles typically extend below ground level, providing the necessary support particularly in situations where the soil conditions at the surface are unsuitable for direct load-bearing, or when the water table is high. In essence, piles are integral to the overall design and functionality of a bridge's substructure, ensuring that forces are properly distributed and that the bridge remains stable throughout its lifespan.