Which structure is essential for ensuring stability when excessive loads are applied on a bridge?

The substructure is essential for ensuring stability when excessive loads are applied to a bridge. It forms the part of the bridge that supports and transfers loads from the superstructure to the foundation and ultimately to the ground. This includes elements such as foundations, piers, and abutments, which play a critical role in maintaining the overall structural integrity of the bridge under various load conditions.

In scenarios where excessive loads are encountered, the substructure must effectively distribute these loads and ensure that there is no excessive settlement or movement. A well-designed substructure is crucial, especially for bridges spanning large distances or those situated in areas where soil conditions may vary significantly.

The superstructure, while vital as it carries the live loads, relies on the substructure for support. Decking is the surface of the bridge that vehicles travel on, and although it needs to be strong, it is the substructure that ultimately prevents failure under heavy loads. Pavement refers to the surface material applied on top of the decking to provide a smooth ride and traction for vehicles, but it does not contribute to the structural stability of the bridge itself. Thus, the substructure is the key component that ensures stability when bridges are subjected to excessive loads.