US Bridges

Forest Road over Coal Creek

Fair

Flathead County, Montana · Coal Creek Road · Structure no. 011007000000055

Built
1964
61 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
49 ft
1 main span
Daily traffic
10
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 1964, so it is 61 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 10 vehicles a day, projected to reach 15 by 2045. The structure is 49 ft (14.9 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
CrossesCoal Creek
LocationCoal Creek Road
RouteFederal Lands Road 317
CountyFlathead County
StateMontana
Coordinates48.66203, -114.24274
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 inspectionAugust 2023
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 geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating20.4 US tons
Inventory rating15.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadHS 20
Structure length49 ft (14.9 m)
Longest span48 ft (14.6 m)
Deck width15 ft (4.6 m)
Roadway width14 ft (4.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic10 (1992)
Projected traffic15 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 1964, making it 61 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 10 vehicles per day (1992 count).

How long is Forest Road over Coal Creek?

The structure is 49 ft (14.9 m) long with a longest span of 48 ft (14.6 m) and a deck 15 ft wide.

Who owns Forest Road over Coal Creek?

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