US Bridges

SH 28 over Lemhi River

Good

Lemhi County, Idaho · 12 N. Leadore · Structure no. 000000000013386

Built
2018
7 years old
Condition
Good
inspected August 2024
Type
Slab
Prestressed Concrete
Length
85 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 2018, so it is 7 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 9 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 85 ft (25.9 m) long and 44 ft wide. If it were closed, the detour would be 78.3 mi (126 km).

CarriesSH 28
CrossesLemhi River
Location12 N. Leadore
RouteState Highway 28
StateIdaho
Coordinates44.78089, -113.54503
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
Deck9 ExcellentNo problems noted.
Superstructure9 ExcellentNo problems noted.
Substructure9 ExcellentNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionAugust 2024
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation9: Superior 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 rating70.3 US tons
Inventory rating43.5 US tons

Structure

Structure typeSlab
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans1
Design loadHL 93
Structure length85 ft (25.9 m)
Longest span82 ft (25 m)
Deck width44 ft (13.4 m)
Roadway width41 ft (12.6 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 2018, making it 7 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 2024.

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 85 ft (25.9 m) long with a longest span of 82 ft (25 m) and a deck 44 ft wide.

Who owns SH 28 over Lemhi River?

It is owned by the State Highway Agency.