US Bridges

SH 28 over Lemhi River

Good

Lemhi County, Idaho · 19.6 N. Leadore. · Structure no. 000000000013411

Built
2019
6 years old
Condition
Good
inspected August 2022
Type
Slab
Prestressed Concrete
Length
81 ft
1 main span
Daily traffic
860
2023 count
Owner
State
State Highway Agency

About this bridge

SH 28 over Lemhi River is a prestressed concrete slab carrying SH 28 over Lemhi River in Lemhi County, Idaho. It was built in 2019, so it is 6 years old, younger than the Idaho average of 45.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 860 vehicles a day, roughly 25% of them trucks, projected to reach 1,290 by 2042. The structure is 81 ft (24.7 m) long and 44 ft wide. If it were closed, the detour would be 78.3 mi (126 km).

CarriesSH 28
CrossesLemhi River
Location19.6 N. Leadore.
RouteState Highway 28
StateIdaho
Coordinates44.8905, -113.62628
Functional classRural Minor Arterial

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionAugust 2022
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation8: Equal to present desirable criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating74.3 US tons
Inventory rating48.6 US tons

Structure

Structure typeSlab
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans1
Design loadHL 93
Structure length81 ft (24.7 m)
Longest span78 ft (23.8 m)
Deck width44 ft (13.4 m)
Roadway width42 ft (12.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic860 (2023)
Projected traffic1,290 by 2042
Trucks25%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed78.3 mi (126 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was SH 28 over Lemhi River built?

It was built in 2019, making it 6 years old in 2025.

What condition is SH 28 over Lemhi River in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in August 2022.

How much traffic does SH 28 over Lemhi River carry?

About 860 vehicles per day (2023 count), of which roughly 25% are trucks.

How long is SH 28 over Lemhi River?

The structure is 81 ft (24.7 m) long with a longest span of 78 ft (23.8 m) and a deck 44 ft wide.

Who owns SH 28 over Lemhi River?

It is owned by the State Highway Agency.