US Bridges

S 200 over Dearborn River

Fair

Lewis and Clark County, Montana · 25M SW Simms · Structure no. P00024102+05011

Built
1949
76 years old
Condition
Fair
inspected July 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
186 ft
2 main spans
Daily traffic
1,432
2023 count
Owner
State
State Highway Agency

About this bridge

S 200 over Dearborn River is a steel continuous stringer/multi-beam or girder carrying S 200 over Dearborn River in Lewis and Clark County, Montana. It was built in 1949, so it is 76 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 1,432 vehicles a day, roughly 14% of them trucks, projected to reach 1,504 by 2043. The structure is 186 ft (56.7 m) long and 28 ft wide. If it were closed, the detour would be 39.1 mi (63 km).

Location

Open in Google Maps
CarriesS 200
CrossesDearborn River
Location25M SW Simms
RouteState Highway 200
CountyLewis and Clark County
StateMontana
Coordinates47.21934, -112.24211
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation4: Meets minimum tolerable limits to be 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 alignment7: Better than present minimum criteria
Operating rating25 US tons
Inventory rating19 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 15
Structure length186 ft (56.7 m)
Longest span93 ft (28.2 m)
Deck width28 ft (8.5 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,432 (2023)
Projected traffic1,504 by 2043
Trucks14%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed39.1 mi (63 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 Dearborn River built?

It was built in 1949, making it 76 years old in 2025.

What condition is S 200 over Dearborn 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 July 2023.

How much traffic does S 200 over Dearborn River carry?

About 1,432 vehicles per day (2023 count), of which roughly 14% are trucks.

How long is S 200 over Dearborn River?

The structure is 186 ft (56.7 m) long with a longest span of 93 ft (28.2 m) and a deck 28 ft wide.

Who owns S 200 over Dearborn River?

It is owned by the State Highway Agency.