US Bridges

US 30 over Main Canal

Fair

Twin Falls County, Idaho · 1.6 E. Murtaugh · Structure no. 000000000013665

Built
1956
69 years old, rebuilt 2007
Condition
Fair
inspected November 2023
Type
Stringer/Multi-beam or Girder
Concrete
Length
141 ft
3 main spans
Daily traffic
2,900
2023 count
Owner
State
State Highway Agency

About this bridge

US 30 over Main Canal is a concrete stringer/multi-beam or girder carrying US 30 over Main Canal in Twin Falls County, Idaho. It was built in 1956 and reconstructed in 2007, 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 5 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 2,900 vehicles a day, roughly 20% of them trucks, projected to reach 4,350 by 2042. The structure is 141 ft (43 m) long and 33 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

Open in Google Maps
CarriesUS 30
CrossesMain Canal
Location1.6 E. Murtaugh
RouteU.S. Route 30
CountyTwin Falls County
StateIdaho
Coordinates42.47511, -114.13978
Functional classRural Minor Arterial

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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
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
MaterialConcrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length141 ft (43 m)
Longest span46 ft (14 m)
Deck width33 ft (10 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,900 (2023)
Projected traffic4,350 by 2042
Trucks20%
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

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$1.8 million (2021 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was US 30 over Main Canal built?

It was built in 1956, making it 69 years old in 2025. It was reconstructed in 2007.

What condition is US 30 over Main 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 November 2023.

How much traffic does US 30 over Main Canal carry?

About 2,900 vehicles per day (2023 count), of which roughly 20% are trucks.

How long is US 30 over Main Canal?

The structure is 141 ft (43 m) long with a longest span of 46 ft (14 m) and a deck 33 ft wide.

Who owns US 30 over Main Canal?

It is owned by the State Highway Agency.