US Bridges

S 81 over Warm Spring Creek

Fair

Fergus County, Montana · 7M SW Hilger · Structure no. P00081039+02391

Built
1949
76 years old
Condition
Fair
inspected September 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
38 ft
2 main spans
Daily traffic
377
2023 count
Owner
State
State Highway Agency

About this bridge

S 81 over Warm Spring Creek is a wood or timber stringer/multi-beam or girder carrying S 81 over Warm Spring Creek in Fergus County, Montana. It was built in 1949, so it is 76 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 5 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 377 vehicles a day, roughly 8% of them trucks, projected to reach 396 by 2043. The structure is 38 ft (11.6 m) long and 26 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesS 81
CrossesWarm Spring Creek
Location7M SW Hilger
RouteState Highway 81
CountyFergus County
StateMontana
Coordinates47.2078, -109.45163
Functional classRural Minor 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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
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 rating49.1 US tons
Inventory rating34 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans2
Design loadH 15
Structure length38 ft (11.6 m)
Longest span19 ft (5.8 m)
Deck width26 ft (7.9 m)
Roadway width25 ft (7.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic377 (2023)
Projected traffic396 by 2043
Trucks8%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 km)
TollOn a free road
National Highway SystemNo

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 S 81 over Warm Spring Creek built?

It was built in 1949, making it 76 years old in 2025.

What condition is S 81 over Warm 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 S 81 over Warm Spring Creek carry?

About 377 vehicles per day (2023 count), of which roughly 8% are trucks.

How long is S 81 over Warm Spring Creek?

The structure is 38 ft (11.6 m) long with a longest span of 19 ft (5.8 m) and a deck 26 ft wide.

Who owns S 81 over Warm Spring Creek?

It is owned by the State Highway Agency.