Download the FHWA NBI extracts behind PlainBridges: national-bridge-statistics.csv · high-traffic-poor-bridges.csv. National reference on statistics.
Bridge Safety Guides
On this register · 2024 NBI
According to the Federal Highway Administration's 2024 National Bridge Inventory.
42,080 of 623,216 public highway bridges (6.8%) are Poor in the 2024 file. Iowa leads share at 19.16% among 49 large inventories; Texas holds the largest catalog (56,729) at 1.23% Poor.
- 6.8%
- Poor nationwide
- 19.16%
- Iowa · highest share
- 1.14%
- Nevada · lowest share
- 56,729
- Texas inventory
These guides explain the 0–9 ratings, the retired sufficiency score, and how to look up a record. None of them is a live crossing-safety verdict.
Guide catalog by purpose
Exclusive purpose families across all 10 published guides listed below, not a restatement of national Poor share.
Plain-language guides for understanding and using PlainBridges data effectively.
Understanding Bridge Condition Ratings
How FHWA rates bridge deck, superstructure, substructure, and culvert condition on a 0-9 scale, and how to interpret the current Good/Fair/Poor categories.
Bridge Sufficiency Ratings Explained
How the retired 0-100 composite score was calculated, what it historically measured, and why it does not establish current funding eligibility.
How Bridge Safety Ratings Work
What the NBI condition fields do and do not say about a structure, without turning a recorded category into a live crossing verdict.
How Bridge Inspections Work
The federal bridge inspection program, who inspects, how often, what they check, and how inspection data becomes the NBI records on PlainBridges.
How to Report a Damaged or Unsafe Bridge
Who owns the follow-up when a member of the public notices a concern, and how that channel differs from reading an NBI condition category.
Bridge Types and Materials: A Visual Guide
From steel girders to prestressed concrete, the structural types and materials tracked in the National Bridge Inventory and what they reveal about infrastructure age and resilience.
America's Aging Bridge Infrastructure
What NBI data reveals about the age distribution and Poor-condition shares of America's public highway bridges.
How to Check the Bridges You Cross Daily
A practical guide for commuters, how to look up bridge condition data on PlainBridges for bridges on your daily route and what to do with what you find.
How Bridge Repair Gets Funded
Federal, state, and local funding mechanisms for bridge repair, including why retired sufficiency ratings do not establish current eligibility.
Structurally Deficient Bridges: The Retired Term Explained
Why older reports still say structurally deficient, what FHWA replaced it with, and how to read Poor-condition shares without importing the retired label.
Methodology
Our guides are based on publicly available data from authoritative government sources. All statistics, ratings, and figures cited in these guides are drawn directly from official datasets and publications, with sources clearly referenced throughout.
We aim to present complex government data in plain language that is accessible to general audiences. When methodologies differ between data sources or change over time, we note these variations inline. Our editorial process includes regular reviews to ensure accuracy and timeliness of the information presented.
Why PlainBridges Publishes Guides
The data on this site is faithful to the public record, but public records are rarely self-explanatory. Codes, categorical fields, thresholds, and regulatory terminology can confuse even frequent researchers. Our guides translate those specifics into plain English so that a non-expert reader can interpret a record page correctly and so that a professional reader can quickly confirm our interpretation. Guides are written by PlainBridges, drafted by PlainBridges for structure, and reviewed before publication to ensure that the underlying regulation, methodology, or historical context is represented accurately.
What You Will Find Here
Every guide focuses on a single, researchable question, usually something a visitor might type into a search engine. We cite the original source wherever we state a specific regulatory threshold, dollar figure, date, or fact-about-the-world. We do not invent numbers, do not quote unreliable secondary sources, and do not paraphrase source material so aggressively that its meaning shifts. If you notice a factual drift or a sentence where our summary disagrees with the linked source, email the correction and we will update the guide.
Guides Are Not Professional Advice
Reading a guide is a good first step, it orients you to the vocabulary, the process, and the known edge cases. It is not a substitute for talking to a licensed professional. Guides here do not establish a professional relationship, do not constitute advice tailored to your circumstances, and do not account for recent changes that may not yet be reflected in the upstream dataset. Use them to understand what you are looking at and to form better questions to bring to a qualified advisor.
How We Decide What to Write
We pick guide topics by looking at real visitor questions, search queries that land on the site without a good destination, emails from readers asking for explainers, and patterns in the data that deserve a sustained write-up. We favor topics where a short, honest, well-cited guide genuinely helps over topics that merely drive traffic. When we get a topic wrong, we correct it and note the update; when we get feedback that a guide missed an angle, we add a section rather than rewriting from scratch.