US Bridges

NFSR #275 over Rock Creek

Fair

Fergus County, Montana · 5 MI North of Crystal Lk · Structure no. 011504000000054

Built
1954
71 years old
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
29 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 1954, so it is 71 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 29 ft (8.8 m) long and 15 ft wide. If it were closed, the detour would be 98.2 mi (158 km).

Location

Open in Google Maps
CarriesNFSR #275
CrossesRock Creek
Location5 MI North of Crystal Lk
RouteFederal Lands Road 275
CountyFergus County
StateMontana
Coordinates46.85122, -109.50967
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
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJuly 2024
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 geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating23.9 US tons
Inventory rating18.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadHS 20
Structure length29 ft (8.8 m)
Longest span27 ft (8.2 m)
Deck width15 ft (4.6 m)
Roadway width14 ft (4.2 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 1954, making it 71 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 29 ft (8.8 m) long with a longest span of 27 ft (8.2 m) and a deck 15 ft wide.

Who owns NFSR #275 over Rock Creek?

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