What deterioration signs are common on timber bridges?

• A. Rot, insect damage, checks and splits, joint deterioration, and fastener deterioration in wood.
• B. Corrosion of steel tendons
• C. Hydraulic pump failures
• D. Cracking of concrete

Answer: (A)

The signs of deterioration on timber bridges come from the wood itself and how it responds to moisture, decay, and load over time. Rot weakens the wood structure because fungi break down the fibers, reducing strength and stiffness. Insect damage creates hollow or compromised areas in the timber, compromising its ability to carry loads. Checks are small cracks that form along the grain during drying and service, while splits are larger separations that can propagate under repetitive loading. Joint deterioration occurs at the connections between timber members, where fasteners and joints lose their ability to transfer forces effectively. Fastener deterioration involves corrosion or loosening of nails, bolts, or other fasteners, which reduces the clamping and connection strength between wood members.

These indicators are what you’d expect to see when inspecting wood components, and they directly affect the bridge’s load-carrying capacity. Other options describe issues more relevant to different materials or systems (for example, steel tendon corrosion, hydraulic pumps, or concrete cracking), which aren’t the typical deterioration signs for timber framing.