Which structural element supports the bridge deck and transfers loads to foundations?

The structural element that supports the bridge deck and transfers loads to the foundations is indeed the girders. Girders are the main horizontal supports in a bridge structure that bear the weight of the bridge deck, along with any additional loads (such as vehicles, pedestrians, and environmental factors). They function by distributing these loads down to the vertical elements like columns or piers, which then transfer the weight to the foundations.

Girders are designed to handle bending, shear, and axial loads, making them a crucial part of the bridge's structural integrity. They typically span the distance between supports (like piers) and provide the necessary strength and stability for the bridge deck above.

In contrast, piers are vertical supports that elevate and stabilize the bridge, but they do not directly support the bridge deck. Spans refer to the distance between two supports but do not identify a specific component that carries load. Railings, while essential for safety, are not structural elements that support the bridge deck or transfer loads; they simply provide a barrier along the edge of the bridge.