US Bridges

Carbon Ave over Rock Creek 026

Fair

Carbon County, Montana · 1M E Roberts · Structure no. L05117000+02001

Built
1982
43 years old
Condition
Fair
inspected November 2023
Type
Tee Beam
Prestressed Concrete
Length
92 ft
1 main span
Daily traffic
100
2025 count
Owner
County
County Highway Agency

About this bridge

Carbon Ave over Rock Creek 026 is a prestressed concrete tee beam carrying Carbon Ave over Rock Creek 026 in Carbon County, Montana. It was built in 1982, so it is 43 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 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 100 vehicles a day, roughly 3% of them trucks, projected to reach 100 by 2040. The structure is 92 ft (28 m) long and 18 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesCarbon Ave
CrossesRock Creek 026
Location1M E Roberts
RouteCounty Highway 5102
CountyCarbon County
StateMontana
Coordinates45.36043, -109.15806
Functional classRural Minor Collector

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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionNovember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry8: Equal to present desirable criteria
Waterway adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating60 US tons
Inventory rating36 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans1
Design loadHS 20
Structure length92 ft (28 m)
Longest span90 ft (27.4 m)
Deck width18 ft (5.5 m)
Roadway width16 ft (4.8 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 closed5 mi (8 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 Carbon Ave over Rock Creek 026 built?

It was built in 1982, making it 43 years old in 2025.

What condition is Carbon Ave over Rock Creek 026 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 November 2023.

How much traffic does Carbon Ave over Rock Creek 026 carry?

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

How long is Carbon Ave over Rock Creek 026?

The structure is 92 ft (28 m) long with a longest span of 90 ft (27.4 m) and a deck 18 ft wide.

Who owns Carbon Ave over Rock Creek 026?

It is owned by the County Highway Agency.