US Bridges

Flatwillow Road over Flatwilow Creek

Good

Petroleum County, Montana · 12M S Winnett · Structure no. 000000202303875

Built
2023
2 years old
Condition
Good
inspected December 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
60 ft
1 main span
Daily traffic
100
2025 count
Owner
County
County Highway Agency

About this bridge

Flatwillow Road over Flatwilow Creek is a steel stringer/multi-beam or girder carrying Flatwillow Road over Flatwilow Creek in Petroleum County, Montana. It was built in 2023, so it is 2 years old, younger than the Montana average of 47 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 100 vehicles a day, roughly 3% of them trucks, projected to reach 100 by 2040. The structure is 60 ft (18.3 m) long and 24 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

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CarriesFlatwillow Road
CrossesFlatwilow Creek
Location12M S Winnett
RouteCounty Highway 35114
CountyPetroleum County
StateMontana
Coordinates46.8384, -108.40063
Functional classRural Local

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionDecember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation8: Equal to present desirable criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating46.4 US tons
Inventory rating35.7 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadHL 93
Structure length60 ft (18.3 m)
Longest span55 ft (16.9 m)
Deck width24 ft (7.3 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deck99 ft (30.2 m)

Traffic and service

Average daily traffic100 (2025)
Projected traffic100 by 2040
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty 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 Flatwillow Road over Flatwilow Creek built?

It was built in 2023, making it 2 years old in 2025.

What condition is Flatwillow Road over Flatwilow Creek in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in December 2023.

How much traffic does Flatwillow Road over Flatwilow Creek carry?

About 100 vehicles per day (2025 count), of which roughly 3% are trucks.

How long is Flatwillow Road over Flatwilow Creek?

The structure is 60 ft (18.3 m) long with a longest span of 55 ft (16.9 m) and a deck 24 ft wide.

Who owns Flatwillow Road over Flatwilow Creek?

It is owned by the County Highway Agency.