US Bridges

Old HWY 312 over Custer Coulee 171

Fair

Yellowstone County, Montana · 2M E Huntley · Structure no. L56788016+01001

Built
1928
97 years old, rebuilt 1939
Condition
Fair
inspected October 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
27 ft
1 main span
Daily traffic
2,775
2023 count
Owner
State
State Highway Agency

About this bridge

Old HWY 312 over Custer Coulee 171 is a steel stringer/multi-beam or girder carrying Old HWY 312 over Custer Coulee 171 in Yellowstone County, Montana. It was built in 1928 and reconstructed in 1939, so it is 97 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 2,775 vehicles a day, roughly 1% of them trucks, projected to reach 2,914 by 2043. The structure is 27 ft (8.2 m) long and 33 ft wide. If it were closed, the detour would be 13 mi (21 km).

Location

Open in Google Maps
CarriesOld HWY 312
CrossesCuster Coulee 171
Location2M E Huntley
RouteState Highway 56788
CountyYellowstone County
StateMontana
Coordinates45.92145, -108.25481
Functional classRural Major Collector

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating51 US tons
Inventory rating31 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length27 ft (8.2 m)
Longest span25 ft (7.6 m)
Deck width33 ft (10.2 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,775 (2023)
Projected traffic2,914 by 2043
Trucks1%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed13 mi (21 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 Old HWY 312 over Custer Coulee 171 built?

It was built in 1928, making it 97 years old in 2025. It was reconstructed in 1939.

What condition is Old HWY 312 over Custer Coulee 171 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 October 2023.

How much traffic does Old HWY 312 over Custer Coulee 171 carry?

About 2,775 vehicles per day (2023 count), of which roughly 1% are trucks.

How long is Old HWY 312 over Custer Coulee 171?

The structure is 27 ft (8.2 m) long with a longest span of 25 ft (7.6 m) and a deck 33 ft wide.

Who owns Old HWY 312 over Custer Coulee 171?

It is owned by the State Highway Agency.