What structure prevents vehicles from veering off the bridge?

The parapet is a low wall or barrier at the edge of a bridge that serves both aesthetic and safety purposes. Its primary function is to act as a protective barrier, helping to prevent vehicles from veering off the bridge. Parapets can also enhance the structural integrity of the bridge by providing support and preventing water from eroding the bridge edges.

While railings, barriers, and guardrails are designed to improve vehicle safety and prevent accidents, the term "parapet" specifically refers to this particular structure on bridges. Guardrails, for instance, are often seen along roadways to redirect vehicles back onto the road, while barriers typically refer to larger structures that may be used to separate traffic. Railing can be general and may not always meet the design criteria necessary for bridge safety. Therefore, choosing the parapet reflects an understanding of its unique role and construction within bridge engineering.