US Bridges

S 200 over Blackfoot River

Fair

Missoula County, Montana · 10M NE Potomac · Structure no. P00024026+06871

Built
1947
78 years old, rebuilt 1991
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
248 ft
3 main spans
Daily traffic
3,932
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 1947 and reconstructed in 1991, so it is 78 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 3,932 vehicles a day, roughly 4% of them trucks, projected to reach 4,129 by 2043. The structure is 248 ft (75.6 m) long and 42 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

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CarriesS 200
CrossesBlackfoot River
Location10M NE Potomac
RouteState Highway 200
CountyMissoula County
StateMontana
Coordinates46.94494, -113.43184
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure7 GoodSome minor problems.
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 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 geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating50 US tons
Inventory rating39 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length248 ft (75.6 m)
Longest span122 ft (37.2 m)
Deck width42 ft (12.8 m)
Roadway width40 ft (12.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,932 (2023)
Projected traffic4,129 by 2043
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 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 1947, making it 78 years old in 2025. It was reconstructed in 1991.

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 3,932 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is S 200 over Blackfoot River?

The structure is 248 ft (75.6 m) long with a longest span of 122 ft (37.2 m) and a deck 42 ft wide.

Who owns S 200 over Blackfoot River?

It is owned by the State Highway Agency.