Which corrosion indicators would you typically look for on steel bridge members?

• A. Rust staining, flaking paint, surface rust.
• B. Flaking paint and loss of cross-section only.
• C. Rust staining, flaking paint, surface rust, pitting, and loss of cross-section.
• D. Delamination of concrete.

Answer: (C)

Visual signs of corrosion on steel bridge members come from how steel deteriorates when exposed to moisture and salts. Rust staining shows corrosion products migrating to the surface, leaving reddish-brown marks. Surface rust is a thin layer indicating active corrosion just under the coating. Flaking paint signals coating failure, which allows moisture and chlorides to reach the steel and accelerate deterioration. Pitting is a localized, deeper form of corrosion that creates small holes, which can undermine strength even if the overall surface looks decent. Loss of cross-section represents actual material thinning, directly reducing structural capacity and requiring action. Delamination of concrete isn’t a typical indicator for steel members, since that points to concrete distress rather than the steel itself. So the combination of rust staining, flaking paint, surface rust, pitting, and loss of cross-section covers the range of common steel corrosion indicators you’d look for.