Structure L56999000+00501 · Yellowstone County, MT

S 8th AVE over Sep I 90 010

Carries S 8th AVE over Sep I 90 010, Laurel-s 8th AVE.

Overall conditionFair

Set by its lowest-rated component: Deck at 5 of 9.

How ratings work
Decksets the rating5/9 · Fair
Superstructure7/9 · Good
Substructure6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT235 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 5/9 · sets the ratingSuperstructure 7/9Substructure 6/9

235 ft end to end, longest span 72 ft: about 3 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.

Built196759 years old
Length234.6 ft71.5 m
Daily traffic100counted 2025
Last inspectedMarch 2023every 24 months

Location

StateMontana
CountyYellowstone
LocationLaurel-s 8th AVE
CarriesS 8th AVE
CrossesSep I 90 010
Coordinates45.66074, -108.78177

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length234.6 ft (71.5 m)
Max Span71.9 ft (21.9 m)
Deck Width33.8 ft (10.3 m)
Deck Area736.5 sq m
Main Spans4
Year Built1967

Traffic

Avg Daily Traffic100 (2025)
Truck Traffic3%
Lanes On Bridge2
Lanes Under Bridge4

Inspection & Ownership

Last InspectionMarch 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure NumberL56999000+00501

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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