NBIS 23 Metrics: What FHWA Expects from Every Bridge Program
From inspection frequencies to reporting timelines, these 23 core metrics define whether your bridge inspection program is truly in compliance with the National Bridge Inspection Standards (NBIS).
These aren’t just checkboxes; they’re federally mandated requirements that shape the integrity and credibility of your entire bridge program.
1. The 23 NBIS Metrics - At a Glance
FHWA evaluates compliance using 23 specific metrics. They span everything from personnel qualifications to data reporting, and they are typically grouped into four key areas:
Group 1: Program & Personnel (Metrics 1–5)
These five metrics ensure your bridge program has the right structure and the right people.
Metric 1 – Program Organization
Metric 2 – Qualifications of Program Manager
Metric 3 – Qualifications of Team Leaders
Metric 4 – Qualifications of Load Rating Engineer
Metric 5 – Qualifications of Underwater Bridge Inspection Diver
Group 2: Inspection Frequencies (Metrics 6–11)
These metrics govern how often different types of inspections must occur — based on bridge risk levels and types.
Metric 6 – Routine Inspection: Lower Risk
Metric 7 – Routine Inspection: Higher Risk
Metric 8 – Underwater Inspection: Lower Risk
Metric 9 – Underwater Inspection: Higher Risk
Metric 10 – Fracture Critical Inspection
Metric 11 – Frequency Criteria Guidelines
Group 3: Inspection Procedures (Metrics 12–21)
This is the most detailed group, covering how inspections are conducted and documented.
Metric 12 – Inspection Quality
Metric 13 – Load Rating
Metric 14 – Load Posting or Restrictions
Metric 15 – Bridge File Requirements
Metric 16 – Fracture Critical Members
Metric 17 – Underwater Evaluation Standards
Metric 18 – Scour Assessment
Metric 19 – Complex Bridge Inspection
Metric 20 – QA/QC Program
Metric 21 – Critical Findings Protocols
Group 4: Data & Reporting (Metrics 22–23)
These final two metrics define how data must be maintained and reported to ensure system-wide trust and readiness.
Metric 22 – Preparation and Recordkeeping
Metric 23 – Timely Updates to the National Bridge Inventory (NBI)
2. Why These Metrics Matter
The NBIS 23 Metrics form the foundation for national consistency. They ensure that:
Bridge conditions are routinely and reliably assessed
Inspection programs are professionally staffed and documented
Safety-related findings are acted upon promptly
States maintain a defensible, traceable record of program performance
Ultimately, these metrics help safeguard infrastructure, reduce risk, and build public trust.
3. What FHWA Looks for During Reviews
Annual Compliance Reviews
Each year, FHWA Division Offices evaluate whether your program is meeting these expectations.
What to Expect:
Schedule: Annual or rotational, depending on your state
Approach: Random sampling across bridge types and inspection categories
Focus: Documentation, team qualifications, QA/QC processes, and field practices
4. What Compliance Actually Means
Your program’s status is categorized into four compliance levels:
Staying Ready
To remain audit-ready:
Keep all documentation and training records updated
Perform internal QA/QC checks
Regularly review bridge files and inspection procedures
Be proactive about aligning with the NBIS metrics year-round
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