US Bridges

Derby Gulch Road over West Bridger Creek

Good

Sweet Grass County, Montana · No Data Entered · Structure no. 011101000011507

Built
2007
18 years old
Condition
Good
inspected September 2024
Type
Slab
Wood or Timber
Length
28 ft
1 main span
Daily traffic
40
Owner
Federal
U.S. Forest Service

About this bridge

Derby Gulch Road over West Bridger Creek is a wood or timber slab carrying Derby Gulch Road over West Bridger Creek in Sweet Grass County, Montana. It was built in 2007, so it is 18 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 28 ft (8.5 m) long and 16 ft wide. If it were closed, the detour would be 620.7 mi (999 km).

Location

Open in Google Maps
CarriesDerby Gulch Road
CrossesWest Bridger Creek
LocationNo Data Entered
RouteFederal Lands Road 6674
CountySweet Grass County
StateMontana
Coordinates45.60919, -109.82165
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
Deck8 Very GoodNo problems noted.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionSeptember 2024
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 geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating61.1 US tons
Inventory rating47.2 US tons

Structure

Structure typeSlab
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadH 20
Structure length28 ft (8.5 m)
Longest span27 ft (8.2 m)
Deck width16 ft (4.9 m)
Roadway width14 ft (4.3 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 closed620.7 mi (999 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 Derby Gulch Road over West Bridger Creek built?

It was built in 2007, making it 18 years old in 2025.

What condition is Derby Gulch Road over West Bridger 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 September 2024.

How much traffic does Derby Gulch Road over West Bridger Creek carry?

About 40 vehicles per day (latest count).

How long is Derby Gulch Road over West Bridger Creek?

The structure is 28 ft (8.5 m) long with a longest span of 27 ft (8.2 m) and a deck 16 ft wide.

Who owns Derby Gulch Road over West Bridger Creek?

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