US Bridges

I 15 Nbl & Sbl over Marsh Creek

Fair

Bannock County, Idaho · 11.1 S. Arimo · Structure no. 000000000011070

Built
1971
54 years old
Condition
Fair
inspected July 2021
Type
Stringer/Multi-beam or Girder
Concrete
Length
44 ft
1 main span
Daily traffic
12,000
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 Nbl & Sbl over Marsh Creek is a concrete stringer/multi-beam or girder carrying I 15 Nbl & Sbl over Marsh Creek in Bannock County, Idaho. It was built in 1971, so it is 54 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 12,000 vehicles a day, roughly 22% of them trucks, projected to reach 18,000 by 2042. The structure is 44 ft (13.4 m) long and 114 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

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CarriesI 15 Nbl & Sbl
CrossesMarsh Creek
Location11.1 S. Arimo
RouteInterstate 15
CountyBannock County
StateIdaho
Coordinates42.42108, -112.18692
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 2021
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating57 US tons
Inventory rating34 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length44 ft (13.4 m)
Longest span42 ft (12.8 m)
Deck width114 ft (34.7 m)
Roadway width111 ft (33.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic12,000 (2023)
Projected traffic18,000 by 2042
Trucks22%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$1.9 million (2021 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was I 15 Nbl & Sbl over Marsh Creek built?

It was built in 1971, making it 54 years old in 2025.

What condition is I 15 Nbl & Sbl over Marsh Creek 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 July 2021.

How much traffic does I 15 Nbl & Sbl over Marsh Creek carry?

About 12,000 vehicles per day (2023 count), of which roughly 22% are trucks.

How long is I 15 Nbl & Sbl over Marsh Creek?

The structure is 44 ft (13.4 m) long with a longest span of 42 ft (12.8 m) and a deck 114 ft wide.

Who owns I 15 Nbl & Sbl over Marsh Creek?

It is owned by the State Highway Agency.