US Bridges

1-LANE Road over Main Fork Rock Creek

Fair

Carbon County, Montana · No Data Entered · Structure no. 010802000000192

Built
1952
73 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
33 ft
1 main span
Daily traffic
50
Owner
Federal
U.S. Forest Service

About this bridge

1-LANE Road over Main Fork Rock Creek is a wood or timber stringer/multi-beam or girder carrying 1-LANE Road over Main Fork Rock Creek in Carbon County, Montana. It was built in 1952, so it is 73 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 50 vehicles a day, projected to reach 75 by 2045. The structure is 33 ft (10 m) long and 15 ft wide. If it were closed, the detour would be 98.2 mi (158 km).

Location

Open in Google Maps
Carries1-LANE Road
CrossesMain Fork Rock Creek
LocationNo Data Entered
RouteFederal Lands Road 2379D
CountyCarbon County
StateMontana
Coordinates45.08589, -109.35081
Functional classRural Local

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.
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 protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating31.4 US tons
Inventory rating24.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadHS 20
Structure length33 ft (10 m)
Longest span31 ft (9.5 m)
Deck width15 ft (4.7 m)
Roadway width14 ft (4.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic50 (—)
Projected traffic75 by 2045
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.2 mi (158 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerU.S. Forest Service
Maintained byU.S. Forest Service
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was 1-LANE Road over Main Fork Rock Creek built?

It was built in 1952, making it 73 years old in 2025.

What condition is 1-LANE Road over Main Fork Rock 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 2023.

How much traffic does 1-LANE Road over Main Fork Rock Creek carry?

About 50 vehicles per day (latest count).

How long is 1-LANE Road over Main Fork Rock Creek?

The structure is 33 ft (10 m) long with a longest span of 31 ft (9.5 m) and a deck 15 ft wide.

Who owns 1-LANE Road over Main Fork Rock Creek?

It is owned by the U.S. Forest Service.