Structure 1792 · San Juan County, NM

Irr/us64/491 Wbl over San Juan River

Carries Irr/us64/491 Wbl over San Juan River, Us-491/us-64 In Shiprock.

Overall conditionPoor

Set by its lowest-rated component: Deck at 3 of 9.

How ratings work
Decksets the rating3/9 · Serious
Superstructure4/9 · Poor
Substructure4/9 · Poor
Channelnot part of overall6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT1,005 FT OVERALL200 FT0ELEVATION · LENGTHS TO SCALE
Deck 3/9 · sets the ratingSuperstructure 4/9Substructure 4/9

1,005 ft end to end, longest span 166 ft: about 2.8 football fields. Lengths and the semi-truck on the deck are drawn to the same scale. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a through truss.

Built193690 years old
Length1004.9 ft306.3 m
Daily traffic16,829counted 2023
Last inspectedFebruary 2024every 12 months

Location

StateNew Mexico
CountySan Juan
LocationUs-491/us-64 In Shiprock
CarriesIrr/us64/491 Wbl
CrossesSan Juan River
Coordinates36.78122, -108.69206

Physical Characteristics

MaterialSteel
DesignTruss - Thru
Total Length1004.9 ft (306.3 m)
Max Span166.0 ft (50.6 m)
Deck Width35.1 ft (10.7 m)
Deck Area3277.4 sq m
Main Spans6
Year Built1936

Traffic

Avg Daily Traffic16,829 (2023)
Truck Traffic13%
Lanes On Bridge2

Inspection & Ownership

Last InspectionFebruary 2024
Inspection FrequencyEvery 12 months
OwnerState Highway Agency
Historical SignificanceBridge is eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number000000000001792

How Bridge Ratings Work

Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."

0Failed
1Imminent failure
2Critical
3Serious
4Poor
5Fair
6Satisfactory
7Good
8Very good
9Excellent
Good · lowest component 7–9
Fair · lowest component 5–6
Poor · lowest component 0–4

A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.

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