How do scour-critical bridges differ from ordinary bridges in NBIS?

• A. They require special attention to foundation stability and erosion around piers/abutments; may trigger remedial actions.
• B. They are exempt from NBIS reporting.
• C. They do not require maintenance.
• D. They are only evaluated during flood events.

Answer: (A)

Scour-critical bridges are those where erosion around the foundation could undermine stability. In NBIS, these bridges receive special attention to foundation stability and erosion around piers and abutments, and their condition may trigger remedial actions to protect or restore foundation support. This focus matters because scour can undermine foundations even when the visible superstructure looks fine, so monitoring and potential mitigation are prioritized. The other statements aren’t correct because NBIS reporting applies to scour-critical bridges, maintenance is ongoing, and evaluations aren’t limited to flood events.