US Bridges

S Main ST over Rock Creek 046

Fair

Carbon County, Montana · Joliet · Structure no. L05101000+01001

Built
1987
38 years old
Condition
Fair
inspected October 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
139 ft
2 main spans
Daily traffic
896
2023 count
Owner
County
County Highway Agency

About this bridge

S Main ST over Rock Creek 046 is a steel continuous stringer/multi-beam or girder carrying S Main ST over Rock Creek 046 in Carbon County, Montana. It was built in 1987, so it is 38 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 896 vehicles a day, roughly 3% of them trucks, projected to reach 954 by 2043. The structure is 139 ft (42.5 m) long and 33 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

Open in Google Maps
CarriesS Main ST
CrossesRock Creek 046
LocationJoliet
RouteCounty Highway 5101
CountyCarbon County
StateMontana
Coordinates45.48109, -108.96797
Functional classRural Major 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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
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 typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length139 ft (42.5 m)
Longest span68 ft (20.7 m)
Deck width33 ft (10 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic896 (2023)
Projected traffic954 by 2043
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 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 S Main ST over Rock Creek 046 built?

It was built in 1987, making it 38 years old in 2025.

What condition is S Main ST over Rock Creek 046 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 October 2024.

How much traffic does S Main ST over Rock Creek 046 carry?

About 896 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is S Main ST over Rock Creek 046?

The structure is 139 ft (42.5 m) long with a longest span of 68 ft (20.7 m) and a deck 33 ft wide.

Who owns S Main ST over Rock Creek 046?

It is owned by the County Highway Agency.