US Bridges

SH 29 over Lemhi River

Good

Lemhi County, Idaho · In Leadore · Structure no. 000000000013450

Built
1972
53 years old
Condition
Good
inspected August 2024
Type
Frame
Concrete
Length
23 ft
1 main span
Daily traffic
180
2023 count
Owner
State
State Highway Agency

About this bridge

SH 29 over Lemhi River is a concrete frame carrying SH 29 over Lemhi River in Lemhi County, Idaho. It was built in 1972, so it is 53 years old, older 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 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 180 vehicles a day, roughly 13% of them trucks, projected to reach 270 by 2042. The structure is 23 ft (7 m) long and 32 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

CarriesSH 29
CrossesLemhi River
LocationIn Leadore
RouteState Highway 29
StateIdaho
Coordinates44.68208, -113.35644
Functional classRural Major Collector

Condition and inspection

Good

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

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
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 evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating69 US tons
Inventory rating41 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length23 ft (7 m)
Longest span23 ft (7 m)
Deck width32 ft (9.7 m)
Roadway width29 ft (8.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic180 (2023)
Projected traffic270 by 2042
Trucks13%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 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 29 over Lemhi River built?

It was built in 1972, making it 53 years old in 2025.

What condition is SH 29 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 29 over Lemhi River carry?

About 180 vehicles per day (2023 count), of which roughly 13% are trucks.

How long is SH 29 over Lemhi River?

The structure is 23 ft (7 m) long with a longest span of 23 ft (7 m) and a deck 32 ft wide.

Who owns SH 29 over Lemhi River?

It is owned by the State Highway Agency.