If a bridge is built on horizontal curves, the movement of a vehicle along curves will cause this force on the superstructure.

• A. Longitudinal Forces
• B. Centrifugal Force
• C. Buoyancy Effect
• D. Water Current

Answer: (B)

When a vehicle moves around a horizontal curve, its inertia tends to keep it going straight. To follow the curved path, the structure must provide an inward (centripetal) force, and in the bridge’s frame of reference this outward push on the deck and superstructure is modeled as a centrifugal force. This horizontal outward load increases with the vehicle’s speed and decreases with a larger curve radius, following the idea F ≈ m v^2 / r for the moving vehicle. This is the force the bridge must resist to maintain stability through the curve.

Longitudinal forces would come from speeding up or braking along the direction of travel, not from curving motion. Buoyancy and water current relate to fluids and are not relevant to the structural response of a bridge on a dry, curved alignment.