Sources & method
Inventory. Idaho Transportation Department open GIS
(IdahoTransportationLayersForOpenData ) — 4,273 structures with 40 published
fields, and 2,116 pavement segments. 62 structures in that layer carry coordinates outside Idaho and
are not shown. There is no tile basemap: the outline is drawn from ITD’s own state-highway geometry.
Condition history. FHWA National Bridge Inventory, annual
files 2016–2024, matched to 3,649 of these structures. Ratings are 0–9 integers assigned by
human inspectors, typically on a two-year cycle, so a change is dated to an inspection rather than to
the day it happened.
Construction cost. ITD’s published item-level
bid history — 216,414 rows across 1,172 contracts, 2013–2026. A contract is tied to a
structure by record linkage on its free-text project description, because the two records share
no key. Those links are candidates for review, never facts . Of 240 bridge contracts,
61 resolve to a single structure — 109 are ambiguous, 28 match nothing,
and 42 are blanket programme work that cannot map to one asset at all. Only the 61 appear on
this map, so what you see is the successful quarter, not the whole record. A linked figure is
the structure pay items only (a median 27% of the award), never the whole contract.
Satellite measurability. Our own coherence census of NASA/JPL
OPERA DISP-S1 surface displacement — 149 Sentinel-1 passes, 2016–2025, over frame F38494 in north
Idaho; 556 structures covered so far, statewide coverage exists and simply has not been processed.
A measurable pixel resolves motion to roughly ±1 mm/yr, but it spans 30 m, so it
reports the settlement of a structure and its approaches — never the condition of a deck.
Moscow, Idaho