US Bridges

NFSR #275 over Rock Creek

Fair

Fergus County, Montana · 3 Mi. N. of Crystal Lake · Structure no. 011504000000055

Built
1938
87 years old
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
26 ft
1 main span
Daily traffic
50
Owner
Federal
U.S. Forest Service

About this bridge

NFSR #275 over Rock Creek is a wood or timber stringer/multi-beam or girder carrying NFSR #275 over Rock Creek in Fergus County, Montana. It was built in 1938, so it is 87 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 50 vehicles a day, projected to reach 75 by 2045. The structure is 26 ft (7.8 m) long and 22 ft wide. If it were closed, the detour would be 98.2 mi (158 km).

Location

Open in Google Maps
CarriesNFSR #275
CrossesRock Creek
Location3 Mi. N. of Crystal Lake
RouteFederal Lands Road 275
CountyFergus County
StateMontana
Coordinates46.81317, -109.49715
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.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating22.8 US tons
Inventory rating17.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadHS 15
Structure length26 ft (7.8 m)
Longest span22 ft (6.8 m)
Deck width22 ft (6.6 m)
Roadway width20 ft (6.2 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 NFSR #275 over Rock Creek built?

It was built in 1938, making it 87 years old in 2025.

What condition is NFSR #275 over 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 July 2024.

How much traffic does NFSR #275 over Rock Creek carry?

About 50 vehicles per day (latest count).

How long is NFSR #275 over Rock Creek?

The structure is 26 ft (7.8 m) long with a longest span of 22 ft (6.8 m) and a deck 22 ft wide.

Who owns NFSR #275 over Rock Creek?

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