US Bridges

Forest Road over Griffin Creek

Fair

Flathead County, Montana · Muskrat Road · Structure no. 011008000000106

Built
1970
55 years old
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
32 ft
1 main span
Daily traffic
30
1992 count
Owner
Federal
U.S. Forest Service

About this bridge

Forest Road over Griffin Creek is a wood or timber stringer/multi-beam or girder carrying Forest Road over Griffin Creek in Flathead County, Montana. It was built in 1970, so it is 55 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 30 vehicles a day, projected to reach 45 by 2045. The structure is 32 ft (9.9 m) long and 15 ft wide. If it were closed, the detour would be 98.2 mi (158 km).

Location

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CarriesForest Road
CrossesGriffin Creek
LocationMuskrat Road
RouteFederal Lands Road 9784
CountyFlathead County
StateMontana
Coordinates48.32232, -114.74595
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating45.7 US tons
Inventory rating35.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadHS 20
Structure length32 ft (9.9 m)
Longest span31 ft (9.4 m)
Deck width15 ft (4.6 m)
Roadway width14 ft (4.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic30 (1992)
Projected traffic45 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 Forest Road over Griffin Creek built?

It was built in 1970, making it 55 years old in 2025.

What condition is Forest Road over Griffin 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 Forest Road over Griffin Creek carry?

About 30 vehicles per day (1992 count).

How long is Forest Road over Griffin Creek?

The structure is 32 ft (9.9 m) long with a longest span of 31 ft (9.4 m) and a deck 15 ft wide.

Who owns Forest Road over Griffin Creek?

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