US Bridges

I 15 Nbl over Great Western Canal

Fair

Bonneville County, Idaho · 4.1 N. Idaho Falls · Structure no. 000000000011745

Built
1962
63 years old
Condition
Fair
inspected November 2024
Type
Stringer/Multi-beam or Girder
Concrete
Length
80 ft
2 main spans
Daily traffic
3,200
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 Nbl over Great Western Canal is a concrete stringer/multi-beam or girder carrying I 15 Nbl over Great Western Canal in Bonneville County, Idaho. It was built in 1962, so it is 63 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 3,200 vehicles a day, roughly 25% of them trucks, projected to reach 4,800 by 2042. The structure is 80 ft (24.4 m) long and 40 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

CarriesI 15 Nbl
CrossesGreat Western Canal
Location4.1 N. Idaho Falls
RouteInterstate 15
StateIdaho
Coordinates43.55243, -112.07208
Functional classRural Principal Arterial - Interstate

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionNovember 2024
Inspection intervalevery 48 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 rating59 US tons
Inventory rating36 US tons

Structure

MaterialConcrete
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length80 ft (24.4 m)
Longest span39 ft (11.9 m)
Deck width40 ft (12.2 m)
Roadway width38 ft (11.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,200 (2023)
Projected traffic4,800 by 2042
Trucks25%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

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 I 15 Nbl over Great Western Canal built?

It was built in 1962, making it 63 years old in 2025.

What condition is I 15 Nbl over Great Western 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 I 15 Nbl over Great Western Canal carry?

About 3,200 vehicles per day (2023 count), of which roughly 25% are trucks.

How long is I 15 Nbl over Great Western Canal?

The structure is 80 ft (24.4 m) long with a longest span of 39 ft (11.9 m) and a deck 40 ft wide.

Who owns I 15 Nbl over Great Western Canal?

It is owned by the State Highway Agency.