US Bridges

Forest Road over Coal Creek

Fair

Flathead County, Montana · Coal Creek Road · Structure no. 011007000000056

Built
1961
64 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
40 ft
1 main span
Daily traffic
5
1992 count
Owner
Federal
U.S. Forest Service

About this bridge

Forest Road over Coal Creek is a wood or timber stringer/multi-beam or girder carrying Forest Road over Coal Creek in Flathead County, Montana. It was built in 1961, so it is 64 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 5 vehicles a day, projected to reach 7 by 2045. The structure is 40 ft (12.2 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
CrossesCoal Creek
LocationCoal Creek Road
RouteFederal Lands Road 317
CountyFlathead County
StateMontana
Coordinates48.69084, -114.37535
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 protection8 Very GoodNo problems noted.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
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 alignment6: Equal to present minimum criteria
Operating rating42.1 US tons
Inventory rating32.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadH 20
Structure length40 ft (12.2 m)
Longest span39 ft (11.9 m)
Deck width15 ft (4.6 m)
Roadway width14 ft (4.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5 (1992)
Projected traffic7 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 Coal Creek built?

It was built in 1961, making it 64 years old in 2025.

What condition is Forest Road over Coal 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 August 2023.

How much traffic does Forest Road over Coal Creek carry?

About 5 vehicles per day (1992 count).

How long is Forest Road over Coal Creek?

The structure is 40 ft (12.2 m) long with a longest span of 39 ft (11.9 m) and a deck 15 ft wide.

Who owns Forest Road over Coal Creek?

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