US Bridges

S 7 over Drainage-Stockpass

Fair

Wibaux County, Montana · 17M S Wibaux · Structure no. P00027061+09791

Built
1941
84 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
57 ft
3 main spans
Daily traffic
628
2023 count
Owner
State
State Highway Agency

About this bridge

S 7 over Drainage-Stockpass is a wood or timber stringer/multi-beam or girder carrying S 7 over Drainage-Stockpass in Wibaux County, Montana. It was built in 1941, so it is 84 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 628 vehicles a day, roughly 18% of them trucks, projected to reach 659 by 2043. The structure is 57 ft (17.4 m) long and 26 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesS 7
CrossesDrainage-Stockpass
Location17M S Wibaux
RouteState Highway 7
CountyWibaux County
StateMontana
Coordinates46.74475, -104.23569
Functional classRural Minor Arterial

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.
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 geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating46 US tons
Inventory rating32 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans3
Design loadH 15
Structure length57 ft (17.4 m)
Longest span19 ft (5.8 m)
Deck width26 ft (7.9 m)
Roadway width25 ft (7.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic628 (2023)
Projected traffic659 by 2043
Trucks18%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was S 7 over Drainage-Stockpass built?

It was built in 1941, making it 84 years old in 2025.

What condition is S 7 over Drainage-Stockpass 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 S 7 over Drainage-Stockpass carry?

About 628 vehicles per day (2023 count), of which roughly 18% are trucks.

How long is S 7 over Drainage-Stockpass?

The structure is 57 ft (17.4 m) long with a longest span of 19 ft (5.8 m) and a deck 26 ft wide.

Who owns S 7 over Drainage-Stockpass?

It is owned by the State Highway Agency.