US Bridges

Stp 7391;S. Main over Portneuf River

Fair

Bannock County, Idaho · 2.0 S. Pocatello · Structure no. 000000000021515

Built
1967
58 years old
Condition
Fair
inspected April 2023
Type
Tee Beam
Prestressed Concrete
Length
117 ft
3 main spans
Daily traffic
6,500
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Stp 7391;S. Main over Portneuf River is a prestressed concrete tee beam carrying Stp 7391;S. Main over Portneuf River in Bannock County, Idaho. It was built in 1967, so it is 58 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 6,500 vehicles a day, roughly 7% of them trucks, projected to reach 9,750 by 2042. The structure is 117 ft (35.7 m) long and 47 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesStp 7391;S. Main
CrossesPortneuf River
Location2.0 S. Pocatello
RouteCounty Highway 7391
CountyBannock County
StateIdaho
Coordinates42.84253, -112.42869
Functional classUrban Other Principal 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 protection8 Very GoodNo problems noted.
Last inspectionApril 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 geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating48 US tons
Inventory rating25 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadH 20
Structure length117 ft (35.7 m)
Longest span40 ft (12.2 m)
Deck width47 ft (14.2 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,500 (2023)
Projected traffic9,750 by 2042
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed3.1 mi (5 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$2.3 million (2023 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Stp 7391;S. Main over Portneuf River built?

It was built in 1967, making it 58 years old in 2025.

What condition is Stp 7391;S. Main over Portneuf River 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 April 2023.

How much traffic does Stp 7391;S. Main over Portneuf River carry?

About 6,500 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is Stp 7391;S. Main over Portneuf River?

The structure is 117 ft (35.7 m) long with a longest span of 40 ft (12.2 m) and a deck 47 ft wide.

Who owns Stp 7391;S. Main over Portneuf River?

It is owned by the City or Municipal Highway Agency.