US Bridges

Larson Loop RD over Box Elder Creek

Good

Carter County, Montana · 30 M S Ekalaka · Structure no. 000000202002429

Built
2019
6 years old
Condition
Good
inspected October 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
151 ft
2 main spans
Daily traffic
100
2025 count
Owner
County
County Highway Agency

About this bridge

Larson Loop RD over Box Elder Creek is a steel stringer/multi-beam or girder carrying Larson Loop RD over Box Elder Creek in Carter County, Montana. It was built in 2019, so it is 6 years old, younger than the Montana average of 47 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 100 vehicles a day, roughly 3% of them trucks, projected to reach 100 by 2040. The structure is 151 ft (46.1 m) long and 25 ft wide. If it were closed, the detour would be 0.6 mi (1 km).

CarriesLarson Loop RD
CrossesBox Elder Creek
Location30 M S Ekalaka
RouteCounty Highway 644
StateMontana
Coordinates45.54559, -104.42475
Functional classRural Local

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation8: Equal to present desirable criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating59 US tons
Inventory rating45 US tons

Structure

MaterialSteel
DeckCorrugated steel
Main spans2
Design loadHL 93
Structure length151 ft (46.1 m)
Longest span74 ft (22.5 m)
Deck width25 ft (7.6 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic100 (2025)
Projected traffic100 by 2040
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed0.6 mi (1 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was Larson Loop RD over Box Elder Creek built?

It was built in 2019, making it 6 years old in 2025.

What condition is Larson Loop RD over Box Elder Creek in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in October 2024.

How much traffic does Larson Loop RD over Box Elder Creek carry?

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

How long is Larson Loop RD over Box Elder Creek?

The structure is 151 ft (46.1 m) long with a longest span of 74 ft (22.5 m) and a deck 25 ft wide.

Who owns Larson Loop RD over Box Elder Creek?

It is owned by the County Highway Agency.