During bridge repairs, which practice helps maintain structural redundancy to reduce dynamic effects?

• A. Use detours during repairs
• B. Staged closures
• C. Limit loads during critical phases
• D. Maintain alternate load paths

Answer: (D)

Maintaining alternate load paths keeps the bridge capable of carrying loads even if some members are temporarily out of service or weakened during repairs. When multiple routes exist for loads to travel through the structure, the removal or reduced capacity of one element doesn’t force others to take an excessive share. That preserves stiffness distribution and dynamic behavior, helping to dampen or limit dynamic effects like amplified vibrations or sudden changes in response that could lead to progressive damage.

Other practices can reduce loads or traffic-related dynamic effects, but they don’t ensure the internal redundancy of the bridge’s load-carrying system. Detours or staged closures change where forces go or how many vehicles are on the structure, and limiting loads reduces the magnitude of dynamic loads, but neither guarantees multiple reliable paths within the bridge itself for carrying those loads if elements are compromised.