Frequently Asked Questions

PlainBridge covers 575,000+ public highway bridges across all 50 states and territories, sourced from the FHWA National Bridge Inventory — the federal database that has tracked bridge conditions since 1968.

A bridge is classified as Structurally Deficient (SD) when it has a significant structural deficiency — typically one or more components rated 4 or below on the FHWA 0–9 scale, or when load-carrying capacity has been restricted. Crucially, 'Structurally Deficient' does NOT mean the bridge is unsafe or about to collapse. It means the bridge needs attention, repair, or more frequent monitoring.

FHWA inspectors rate each major component (deck, superstructure, substructure) on a 0–9 scale. 9 = Excellent condition. 7–8 = Good. 5–6 = Fair. 4 = Poor, with advanced deterioration. 3 = Serious deterioration. 2 = Critical condition. 1–0 = Failed or completely failed condition. Bridges rated 4 or below in any major component are classified as 'Poor' by FHWA.

Federal law (the National Bridge Inspection Standards) requires most highway bridges to be inspected at least every 24 months. Many states conduct annual inspections. Underwater components of bridges over navigable waterways may have longer inspection intervals but require specialized inspection when conducted.

FHWA releases updated NBI data annually, typically in spring, covering the prior calendar year. Bridge inspections may have occurred up to 24 months before the NBI dataset was published. We update PlainBridge when new annual NBI data is released.

Yes. Use the search to find bridges by name, county, or state. Each bridge page shows its structural ID, location, condition ratings, sufficiency score, year built, and average daily traffic count.

No. PlainBridge is an independent data portal presenting publicly available FHWA NBI data. We are not affiliated with FHWA, the U.S. Department of Transportation, or any state DOT.