US Bridges

US 87-W Main ST over Big Spring Creek

Fair

Fergus County, Montana · Lewistown-W Main ST · Structure no. P00057081+09861

Built
1962
63 years old
Condition
Fair
inspected September 2024
Type
Tee Beam
Concrete
Length
30 ft
1 main span
Daily traffic
5,357
2023 count
Owner
State
State Highway Agency

About this bridge

US 87-W Main ST over Big Spring Creek is a concrete tee beam carrying US 87-W Main ST over Big Spring Creek in Fergus County, Montana. It was built in 1962, so it is 63 years old, older than the Montana average of 47 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 5,357 vehicles a day, roughly 2% of them trucks, projected to reach 5,625 by 2043. The structure is 30 ft (9.1 m) long and 80 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesUS 87-W Main ST
CrossesBig Spring Creek
LocationLewistown-W Main ST
RouteU.S. Route 87
CountyFergus County
StateMontana
Coordinates47.06607, -109.42509
Functional classUrban Other Principal Arterial

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating42 US tons
Inventory rating33 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 20
Structure length30 ft (9.1 m)
Longest span28 ft (8.5 m)
Deck width80 ft (24.4 m)
Roadway width56 ft (17.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,357 (2023)
Projected traffic5,625 by 2043
Trucks2%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was US 87-W Main ST over Big Spring Creek built?

It was built in 1962, making it 63 years old in 2025.

What condition is US 87-W Main ST over Big Spring Creek in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in September 2024.

How much traffic does US 87-W Main ST over Big Spring Creek carry?

About 5,357 vehicles per day (2023 count), of which roughly 2% are trucks.

How long is US 87-W Main ST over Big Spring Creek?

The structure is 30 ft (9.1 m) long with a longest span of 28 ft (8.5 m) and a deck 80 ft wide.

Who owns US 87-W Main ST over Big Spring Creek?

It is owned by the State Highway Agency.