How often are routine NBIS bridge inspections generally required, and how does this differ for fracture-critical bridges?

• A. Routine inspections at least every 12 months; fracture-critical bridges require inspections at least every 6 months.
• B. Routine inspections at least every 24 months; fracture-critical bridges require inspections at least every 12 months.
• C. Routine every 3 years; fracture-critical bridges require inspections annually.
• D. Routine every 6 months; fracture-critical bridges require inspections at least every 18 months.

Answer: (B)

Routine NBIS inspections are conducted at least every 24 months, and fracture-critical bridges must be inspected at least every 12 months. The difference exists because fracture-critical bridges have no redundant load path, so a single failed member could lead to collapse unless issues are detected and addressed promptly. This yearly inspection helps catch cracking, corrosion, or connection problems early, reducing the risk of unexpected failure. Some jurisdictions may require more frequent checks based on conditions, but these are the NBIS minimums: every two years for routine bridges and every year for fracture-critical ones.