US Bridges

I 15 Nbl over Marsh Valley Road

Fair

Bannock County, Idaho · 13.8 N. Malad · Structure no. 000000000011050

Built
1971
54 years old, rebuilt 1987
Condition
Fair
inspected June 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
127 ft
3 main spans
Daily traffic
6,000
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 Nbl over Marsh Valley Road is a prestressed concrete stringer/multi-beam or girder carrying I 15 Nbl over Marsh Valley Road in Bannock County, Idaho. It was built in 1971 and reconstructed in 1987, 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 6,000 vehicles a day, roughly 23% of them trucks, projected to reach 9,000 by 2042. The structure is 127 ft (38.7 m) long and 44 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI 15 Nbl
CrossesMarsh Valley Road
Location13.8 N. Malad
RouteInterstate 15
CountyBannock County
StateIdaho
Coordinates42.37486, -112.20983
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.
Last inspectionJune 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating45 US tons
Inventory rating27 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length127 ft (38.7 m)
Longest span44 ft (13.4 m)
Deck width44 ft (13.3 m)
Roadway width41 ft (12.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,000 (2023)
Projected traffic9,000 by 2042
Trucks23%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$1.6 million (2018 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I 15 Nbl over Marsh Valley Road built?

It was built in 1971, making it 54 years old in 2025. It was reconstructed in 1987.

What condition is I 15 Nbl over Marsh Valley Road 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 June 2024.

How much traffic does I 15 Nbl over Marsh Valley Road carry?

About 6,000 vehicles per day (2023 count), of which roughly 23% are trucks.

How long is I 15 Nbl over Marsh Valley Road?

The structure is 127 ft (38.7 m) long with a longest span of 44 ft (13.4 m) and a deck 44 ft wide.

Who owns I 15 Nbl over Marsh Valley Road?

It is owned by the State Highway Agency.