{
  "dataset": "bridge-rating-transitions",
  "title": "Every year-on-year movement in the condition ratings of every US bridge, 1992-2025",
  "required_attribution": "The underlying records are the National Bridge Inventory, published by the Federal Highway Administration, United States Department of Transportation. The panel, the classification of each transition and every count are by the Artificial Wasteland.",
  "what_it_is_not": "A reconstruction_recorded value of 0 is not a statement that no work was done on the bridge. Item 106 counts only work that would have been eligible for Federal-aid funding as reconstruction, and the Coding Guide lists eligible work that is expressly not to be counted, including emergency repair after an accident, retrofitting that does not alter geometry or capacity, adding a substructure element or an extra girder, overlaying a deck as part of a larger surfacing project, and painting structural steel. The legacy inventory has no field in which most maintenance can be recorded at all. That is the fact this dataset measures, not a claim that anybody failed to record anything.",
  "what_the_counts_exclude": "A transition is excluded if either rating is not a digit, if the bridge is absent from either snapshot, if item 27 (year built) differs between the two snapshots (a structure number can be reused, and a changed year built means the key is not naming one bridge), or if the structure number appeared more than once in that filing unit's file for that year, which FHWA's own data checks call a fatal error and which happened 2,858 times. Only item 5A record type 1 rows are read; the type 2 and A-to-Y route records published through 2009 share a structure number with the type 1 record and carry no ratings.",
  "sources": [
    {
      "id": "src:fhwa-national-bridge-inventory",
      "title": "National Bridge Inventory, annual delimited snapshots, 1992-2025",
      "publisher": "Federal Highway Administration, United States Department of Transportation",
      "url": "https://www.fhwa.dot.gov/bridge/nbi/ascii.cfm",
      "accessed": "2026-09-13",
      "licence_id": "US-GOV-PD",
      "licence": "Work of the United States Government, not subject to copyright in the United States (17 U.S.C. section 105)",
      "licence_basis": "statute",
      "licence_note": "No licence notice is published with these files, and none is needed: they are prepared by an agency of the United States Government in the course of its official duties, so 17 U.S.C. section 105 puts them outside copyright in the United States. The basis recorded here is the statute rather than a notice, which is what that field is for. 1,782 state-year files were fetched; each one's byte length and sha256 as received is recorded in research/no-field-for-the-repair/data/raw-manifest.json."
    },
    {
      "id": "src:aw-bridge-rating-transitions",
      "title": "The transition census",
      "publisher": "Artificial Wasteland",
      "url": "https://artwaste.land/strata/no-field-for-the-repair/",
      "accessed": "2026-09-13",
      "licence_id": "CC0-1.0",
      "licence": "CC0 1.0 Universal (public domain dedication)",
      "licence_basis": "publisher-statement",
      "licence_note": "Ours, dedicated to the public domain. The exclusions and seven predictions were fixed in research/no-field-for-the-repair/PREREGISTRATION.md and committed before analyse.mjs was written; five held and two broke, and the page says which."
    }
  ],
  "rows": 614614
}