US Bridges

SH 74 over Low Line Canal

Fair

Twin Falls County, Idaho · 3.6 S. Twin Falls · Structure no. 000000000015220

Built
1956
69 years old
Condition
Fair
inspected March 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
78 ft
1 main span
Daily traffic
1,200
2023 count
Owner
State
State Highway Agency

About this bridge

SH 74 over Low Line Canal is a steel stringer/multi-beam or girder carrying SH 74 over Low Line Canal in Twin Falls County, Idaho. It was built in 1956, so it is 69 years old, older than the Idaho average of 45.3 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 1,200 vehicles a day, roughly 26% of them trucks, projected to reach 1,800 by 2042. The structure is 78 ft (23.8 m) long and 37 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesSH 74
CrossesLow Line Canal
Location3.6 S. Twin Falls
RouteState Highway 74
CountyTwin Falls County
StateIdaho
Coordinates42.52028, -114.53231
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.
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 inspectionMarch 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 adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating58 US tons
Inventory rating35.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length78 ft (23.8 m)
Longest span75 ft (22.9 m)
Deck width37 ft (11.2 m)
Roadway width34 ft (10.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,200 (2023)
Projected traffic1,800 by 2042
Trucks26%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was SH 74 over Low Line Canal built?

It was built in 1956, making it 69 years old in 2025.

What condition is SH 74 over Low Line Canal 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 March 2023.

How much traffic does SH 74 over Low Line Canal carry?

About 1,200 vehicles per day (2023 count), of which roughly 26% are trucks.

How long is SH 74 over Low Line Canal?

The structure is 78 ft (23.8 m) long with a longest span of 75 ft (22.9 m) and a deck 37 ft wide.

Who owns SH 74 over Low Line Canal?

It is owned by the State Highway Agency.