US Bridges

S 200 EB over Blackfoot River

Fair

Missoula County, Montana · 5M W Potomac · Structure no. P00024011+01811

Built
1940
85 years old, rebuilt 1991
Condition
Fair
inspected June 2023
Type
Truss - Deck
Steel Continuous
Length
446 ft
3 main spans
Daily traffic
2,314
2023 count
Owner
State
State Highway Agency

About this bridge

S 200 EB over Blackfoot River is a steel continuous truss - deck carrying S 200 EB over Blackfoot River in Missoula County, Montana. It was built in 1940 and reconstructed in 1991, so it is 85 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 2,314 vehicles a day, roughly 5% of them trucks, projected to reach 2,429 by 2043. The structure is 446 ft (135.9 m) long and 25 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesS 200 EB
CrossesBlackfoot River
Location5M W Potomac
RouteState Highway 200
CountyMissoula County
StateMontana
Coordinates46.91058, -113.67567
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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJune 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 geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating43 US tons
Inventory rating26 US tons

Structure

Structure typeTruss - Deck
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 width25 ft (7.5 m)
Roadway width22 ft (6.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,314 (2023)
Projected traffic2,429 by 2043
Trucks5%
Lanes on structure1
Traffic directionOne-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 EB over Blackfoot River built?

It was built in 1940, making it 85 years old in 2025. It was reconstructed in 1991.

What condition is S 200 EB 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 June 2023.

How much traffic does S 200 EB over Blackfoot River carry?

About 2,314 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is S 200 EB 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 25 ft wide.

Who owns S 200 EB over Blackfoot River?

It is owned by the State Highway Agency.