What does the "deck" of the bridge refer to?

The term "deck" in the context of a bridge refers specifically to the surface of the bridge that is used for vehicular and pedestrian traffic. It is the flat, horizontal part that provides the surface for vehicles or people to travel across. The deck is integral to the functionality of the bridge as it directly supports the loads imposed by traffic, and it is typically constructed using materials such as concrete, steel, or timber.

Understanding what comprises the deck is essential for anyone involved in bridge design, inspection, or maintenance, as it plays a vital role in overall bridge safety and performance. The other options represent different components of the bridge: the supporting structure refers to the beams or girders that help hold up the deck; the substructure includes the foundations and piers that support the entire bridge; and the approach road is the roadway leading up to the bridge itself. Each of these components plays a critical role in the bridge's overall integrity, but specifically, the "deck" denotes the surface that accommodates the traffic flow.