US Bridges

US 12 over O`fallon Creek

Fair

Fallon County, Montana · 11M W Plevna · Structure no. P00002058+08011

Built
1971
54 years old
Condition
Fair
inspected October 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
187 ft
3 main spans
Daily traffic
516
2023 count
Owner
State
State Highway Agency

About this bridge

US 12 over O`fallon Creek is a prestressed concrete stringer/multi-beam or girder carrying US 12 over O`fallon Creek in Fallon County, Montana. It was built in 1971, so it is 54 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 516 vehicles a day, roughly 12% of them trucks, projected to reach 542 by 2043. The structure is 187 ft (57 m) long and 40 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesUS 12
CrossesO`fallon Creek
Location11M W Plevna
RouteU.S. Route 12
CountyFallon County
StateMontana
Coordinates46.42098, -104.76067
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating47 US tons
Inventory rating33 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length187 ft (57 m)
Longest span61 ft (18.6 m)
Deck width40 ft (12.3 m)
Roadway width38 ft (11.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic516 (2023)
Projected traffic542 by 2043
Trucks12%
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 US 12 over O`fallon Creek built?

It was built in 1971, making it 54 years old in 2025.

What condition is US 12 over O`fallon 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 October 2024.

How much traffic does US 12 over O`fallon Creek carry?

About 516 vehicles per day (2023 count), of which roughly 12% are trucks.

How long is US 12 over O`fallon Creek?

The structure is 187 ft (57 m) long with a longest span of 61 ft (18.6 m) and a deck 40 ft wide.

Who owns US 12 over O`fallon Creek?

It is owned by the State Highway Agency.