Structure I00090434+00902 · Yellowstone County, MT

I 90 over Int Laurel-p 4-rr

Carries I 90 over Int Laurel-p 4-rr, Laurel.

Overall conditionFair

Set by its lowest-rated component: Deck and Superstructure and Substructure at 6 of 9.

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructuresets the rating6/9 · Satisfactory
Substructuresets the rating6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT366 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 6/9Substructure 6/9

366 ft end to end, longest span 112 ft: about 5 semi-trucks nose to tail. 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 multi-beam bridge.

Built1964rebuilt 2007
Length365.8 ft111.5 m
Daily traffic7,545counted 2023
Last inspectedJune 2023every 24 months

Location

StateMontana
CountyYellowstone
LocationLaurel
CarriesI 90
CrossesInt Laurel-p 4-rr
Coordinates45.66265, -108.76993

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length365.8 ft (111.5 m)
Max Span111.9 ft (34.1 m)
Deck Width44.0 ft (13.4 m)
Deck Area1494.1 sq m
Main Spans2
Year Built1964 (reconstructed 2007)

Traffic

Avg Daily Traffic7,545 (2023)
Truck Traffic18%
Lanes On Bridge2
Lanes Under Bridge4

Inspection & Ownership

Last InspectionJune 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure NumberI00090434+00902

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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