US Bridges

SH 34 over Twin Lakes Canal

Fair

Franklin County, Idaho · 6.2 N. Preston · Structure no. 000000000013990

Built
1958
67 years old
Condition
Fair
inspected November 2024
Type
Frame
Concrete
Length
26 ft
1 main span
Daily traffic
1,200
2023 count
Owner
State
State Highway Agency

About this bridge

SH 34 over Twin Lakes Canal is a concrete frame carrying SH 34 over Twin Lakes Canal in Franklin County, Idaho. It was built in 1958, so it is 67 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 1,200 vehicles a day, roughly 24% of them trucks, projected to reach 1,800 by 2042. The structure is 26 ft (7.9 m) long and 72 ft wide. If it were closed, the detour would be 29.8 mi (48 km).

Location

Open in Google Maps
CarriesSH 34
CrossesTwin Lakes Canal
Location6.2 N. Preston
RouteState Highway 34
CountyFranklin County
StateIdaho
Coordinates42.19122, -111.83325
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating100 US tons
Inventory rating60 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length26 ft (7.9 m)
Longest span26 ft (7.9 m)
Deck width72 ft (22 m)
Roadway width32 ft (9.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,200 (2023)
Projected traffic1,800 by 2042
Trucks24%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed29.8 mi (48 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$476,000 (2020 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SH 34 over Twin Lakes Canal built?

It was built in 1958, making it 67 years old in 2025.

What condition is SH 34 over Twin Lakes 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 2024.

How much traffic does SH 34 over Twin Lakes Canal carry?

About 1,200 vehicles per day (2023 count), of which roughly 24% are trucks.

How long is SH 34 over Twin Lakes Canal?

The structure is 26 ft (7.9 m) long with a longest span of 26 ft (7.9 m) and a deck 72 ft wide.

Who owns SH 34 over Twin Lakes Canal?

It is owned by the State Highway Agency.