US Bridges

Forest Road over Logan Creek

Fair

Flathead County, Montana · Tally Lake Road · Structure no. 011008000000077

Built
1974
51 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
93 ft
1 main span
Daily traffic
60
1992 count
Owner
Federal
U.S. Forest Service

About this bridge

Forest Road over Logan Creek is a prestressed concrete stringer/multi-beam or girder carrying Forest Road over Logan Creek in Flathead County, Montana. It was built in 1974, so it is 51 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 60 vehicles a day, projected to reach 90 by 2045. The structure is 93 ft (28.3 m) long and 29 ft wide. If it were closed, the detour would be 98.2 mi (158 km).

Location

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CarriesForest Road
CrossesLogan Creek
LocationTally Lake Road
RouteFederal Lands Road 913
CountyFlathead County
StateMontana
Coordinates48.42202, -114.62587
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 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 evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry7: Better than present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating82.5 US tons
Inventory rating63.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length93 ft (28.3 m)
Longest span90 ft (27.4 m)
Deck width29 ft (8.9 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic60 (1992)
Projected traffic90 by 2045
Trucks—
Lanes on structure2
Traffic directionTwo-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 Logan Creek built?

It was built in 1974, making it 51 years old in 2025.

What condition is Forest Road over Logan 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 Logan Creek carry?

About 60 vehicles per day (1992 count).

How long is Forest Road over Logan Creek?

The structure is 93 ft (28.3 m) long with a longest span of 90 ft (27.4 m) and a deck 29 ft wide.

Who owns Forest Road over Logan Creek?

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