US Bridges

Cottonwood Lakes over Trail Creek

Good

Missoula County, Montana · Trail Creek Crossing · Structure no. 011606000024391

Built
2011
14 years old
Condition
Good
inspected August 2021
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
57 ft
1 main span
Daily traffic
40
Owner
Federal
U.S. Forest Service

About this bridge

Cottonwood Lakes over Trail Creek is a prestressed concrete stringer/multi-beam or girder carrying Cottonwood Lakes over Trail Creek in Missoula County, Montana. It was built in 2011, so it is 14 years old, younger than the Montana average of 47 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 40 vehicles a day, projected to reach 60 by 2045. The structure is 57 ft (17.4 m) long and 18 ft wide. If it were closed, the detour would be 98.2 mi (158 km).

Location

Open in Google Maps
CarriesCottonwood Lakes
CrossesTrail Creek
LocationTrail Creek Crossing
RouteFederal Lands Road 477
CountyMissoula County
StateMontana
Coordinates47.19047, -113.43465
Functional classRural Local

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure8 Very GoodNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionAugust 2021
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating48.6 US tons
Inventory rating37.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckOther
Main spans1
Design loadHL 93
Structure length57 ft (17.4 m)
Longest span54 ft (16.6 m)
Deck width18 ft (5.6 m)
Roadway width16 ft (4.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic40 (—)
Projected traffic60 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 Cottonwood Lakes over Trail Creek built?

It was built in 2011, making it 14 years old in 2025.

What condition is Cottonwood Lakes over Trail Creek in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in August 2021.

How much traffic does Cottonwood Lakes over Trail Creek carry?

About 40 vehicles per day (latest count).

How long is Cottonwood Lakes over Trail Creek?

The structure is 57 ft (17.4 m) long with a longest span of 54 ft (16.6 m) and a deck 18 ft wide.

Who owns Cottonwood Lakes over Trail Creek?

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