US Bridges

Cinnabar Basin RD over Mulherin Creek 076

Fair

Park County, Montana · 2M W Corwin Springs · Structure no. L34322001+08001

Built
2005
20 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
25 ft
1 main span
Daily traffic
100
2025 count
Owner
County
County Highway Agency

About this bridge

Cinnabar Basin RD over Mulherin Creek 076 is a steel stringer/multi-beam or girder carrying Cinnabar Basin RD over Mulherin Creek 076 in Park County, Montana. It was built in 2005, so it is 20 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 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 100 vehicles a day, roughly 3% of them trucks, projected to reach 100 by 2040. The structure is 25 ft (7.6 m) long and 16 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesCinnabar Basin RD
CrossesMulherin Creek 076
Location2M W Corwin Springs
RouteCounty Highway 34310
CountyPark County
StateMontana
Coordinates45.11976, -110.82027
Functional classRural Local

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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 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 geometry6: Equal to present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating61 US tons
Inventory rating47 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadUnknown
Structure length25 ft (7.6 m)
Longest span20 ft (6.1 m)
Deck width16 ft (4.9 m)
Roadway width15 ft (4.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic100 (2025)
Projected traffic100 by 2040
Trucks3%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty 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 Cinnabar Basin RD over Mulherin Creek 076 built?

It was built in 2005, making it 20 years old in 2025.

What condition is Cinnabar Basin RD over Mulherin Creek 076 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 September 2023.

How much traffic does Cinnabar Basin RD over Mulherin Creek 076 carry?

About 100 vehicles per day (2025 count), of which roughly 3% are trucks.

How long is Cinnabar Basin RD over Mulherin Creek 076?

The structure is 25 ft (7.6 m) long with a longest span of 20 ft (6.1 m) and a deck 16 ft wide.

Who owns Cinnabar Basin RD over Mulherin Creek 076?

It is owned by the County Highway Agency.