US Bridges

US 191 over Specimen Creek

Fair

Gallatin County, Montana · 24M SE Big Sky · Structure no. P00050026+04431

Built
1955
70 years old
Condition
Fair
inspected July 2023
Type
Tee Beam
Concrete Continuous
Length
64 ft
3 main spans
Daily traffic
2,605
2023 count
Owner
State
State Highway Agency

About this bridge

US 191 over Specimen Creek is a concrete continuous tee beam carrying US 191 over Specimen Creek in Gallatin County, Montana. It was built in 1955, so it is 70 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 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 2,605 vehicles a day, roughly 10% of them trucks, projected to reach 2,735 by 2043. The structure is 64 ft (19.4 m) long and 34 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesUS 191
CrossesSpecimen Creek
Location24M SE Big Sky
RouteU.S. Route 191
CountyGallatin County
StateMontana
Coordinates45.0119, -111.08143
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating38 US tons
Inventory rating29 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckOther
Main spans3
Design loadHS 20
Structure length64 ft (19.4 m)
Longest span40 ft (12.2 m)
Deck width34 ft (10.3 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,605 (2023)
Projected traffic2,735 by 2043
Trucks10%
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 US 191 over Specimen Creek built?

It was built in 1955, making it 70 years old in 2025.

What condition is US 191 over Specimen Creek 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 US 191 over Specimen Creek carry?

About 2,605 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is US 191 over Specimen Creek?

The structure is 64 ft (19.4 m) long with a longest span of 40 ft (12.2 m) and a deck 34 ft wide.

Who owns US 191 over Specimen Creek?

It is owned by the State Highway Agency.