US Bridges

IRR - S 313 over Two Leggin Canal

Good

Big Horn County, Montana · 5M S Hardin · Structure no. S00313006+02721

Built
1989
36 years old
Condition
Good
inspected November 2023
Type
Tee Beam
Prestressed Concrete
Length
58 ft
1 main span
Daily traffic
899
2023 count
Owner
State
State Highway Agency

About this bridge

IRR - S 313 over Two Leggin Canal is a prestressed concrete tee beam carrying IRR - S 313 over Two Leggin Canal in Big Horn County, Montana. It was built in 1989, so it is 36 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 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 899 vehicles a day, roughly 17% of them trucks, projected to reach 944 by 2043. The structure is 58 ft (17.7 m) long and 37 ft wide. If it were closed, the detour would be 80.2 mi (129 km).

CarriesIRR - S 313
CrossesTwo Leggin Canal
Location5M S Hardin
RouteState Highway 313
StateMontana
Coordinates45.66568, -107.64469
Functional classRural Major Collector

Condition and inspection

Good

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

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionNovember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating48 US tons
Inventory rating27 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length58 ft (17.7 m)
Longest span56 ft (17.1 m)
Deck width37 ft (11.2 m)
Roadway width34 ft (10.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic899 (2023)
Projected traffic944 by 2043
Trucks17%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed80.2 mi (129 km)
TollOn a free road
National Highway SystemNo

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 IRR - S 313 over Two Leggin Canal built?

It was built in 1989, making it 36 years old in 2025.

What condition is IRR - S 313 over Two Leggin Canal 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 November 2023.

How much traffic does IRR - S 313 over Two Leggin Canal carry?

About 899 vehicles per day (2023 count), of which roughly 17% are trucks.

How long is IRR - S 313 over Two Leggin Canal?

The structure is 58 ft (17.7 m) long with a longest span of 56 ft (17.1 m) and a deck 37 ft wide.

Who owns IRR - S 313 over Two Leggin Canal?

It is owned by the State Highway Agency.