What is a design vehicle (DV) in highway design?

• A. The representative vehicle used to size geometry like turning radii and lane widths.
• B. The smallest vehicle allowed on the highway.
• C. A vehicle used only for maintenance operations.
• D. A vehicle used to test pavement friction.

Answer: (A)

In highway design, the design vehicle is the representative vehicle used to size geometric elements such as turning radii and lane widths. It’s chosen to reflect the most demanding vehicle that will use the road, ensuring the roadway can safely accommodate its turning paths, lane usage, and overall footprint. This means that wider lanes, larger radii, and adequate sight distances are planned so that heavy trucks or buses can maneuver without encroaching on adjacent lanes or creating unsafe conditions. The idea isn’t about the smallest vehicle or maintenance equipment; those roles don’t drive the fundamental geometry. Pavement friction testing relates to surface performance, not how the roadway geometry is sized.