US Bridges

S 200 over Blackfoot River

Fair

Missoula County, Montana · 5M W Potomac · Structure no. P00024011+01812

Built
1988
37 years old
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
446 ft
3 main spans
Daily traffic
4,627
2023 count
Owner
State
State Highway Agency

About this bridge

S 200 over Blackfoot River is a steel continuous stringer/multi-beam or girder carrying S 200 over Blackfoot River in Missoula County, Montana. It was built in 1988, so it is 37 years old, younger 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 6 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 4,627 vehicles a day, roughly 5% of them trucks, projected to reach 4,858 by 2043. The structure is 446 ft (135.9 m) long and 49 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesS 200
CrossesBlackfoot River
Location5M W Potomac
RouteState Highway 200
CountyMissoula County
StateMontana
Coordinates46.91078, -113.67552
Functional classRural Principal Arterial - Other

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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 2024
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 geometry9: Superior to present desirable criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating31 US tons
Inventory rating24 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3 (+2 approach)
Design loadHS 20
Structure length446 ft (135.9 m)
Longest span150 ft (45.7 m)
Deck width49 ft (15 m)
Roadway width46 ft (14.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,627 (2023)
Projected traffic4,858 by 2043
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes

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 200 over Blackfoot River built?

It was built in 1988, making it 37 years old in 2025.

What condition is S 200 over Blackfoot River 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 May 2024.

How much traffic does S 200 over Blackfoot River carry?

About 4,627 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is S 200 over Blackfoot River?

The structure is 446 ft (135.9 m) long with a longest span of 150 ft (45.7 m) and a deck 49 ft wide.

Who owns S 200 over Blackfoot River?

It is owned by the State Highway Agency.