US Bridges

Back Rd; Old Lemhi over Pratt Creek (#1)

Good

Lemhi County, Idaho · 9.0 E. 6.5 S. Salmon · Structure no. 000000000032716

Built
2018
7 years old
Condition
Good
inspected July 2021
Type
Stringer/Multi-beam or Girder
Steel
Length
38 ft
1 main span
Daily traffic
50
2023 count
Owner
County
County Highway Agency

About this bridge

Back Rd; Old Lemhi over Pratt Creek (#1) is a steel stringer/multi-beam or girder carrying Back Rd; Old Lemhi over Pratt Creek (#1) 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 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 50 vehicles a day, roughly 25% of them trucks, projected to reach 75 by 2042. The structure is 38 ft (11.6 m) long and 28 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesBack Rd; Old Lemhi
CrossesPratt Creek (#1)
Location9.0 E. 6.5 S. Salmon
RouteCounty Highway 0
CountyLemhi County
StateIdaho
Coordinates45.07636, -113.69697
Functional classRural Minor Collector

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 protection7 GoodSome minor problems.
Last inspectionJuly 2021
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation8: Equal to present desirable criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating60 US tons
Inventory rating46.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadHL 93
Structure length38 ft (11.6 m)
Longest span35 ft (10.7 m)
Deck width28 ft (8.5 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic50 (2023)
Projected traffic75 by 2042
Trucks25%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty 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 Back Rd; Old Lemhi over Pratt Creek (#1) built?

It was built in 2018, making it 7 years old in 2025.

What condition is Back Rd; Old Lemhi over Pratt Creek (#1) 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 July 2021.

How much traffic does Back Rd; Old Lemhi over Pratt Creek (#1) carry?

About 50 vehicles per day (2023 count), of which roughly 25% are trucks.

How long is Back Rd; Old Lemhi over Pratt Creek (#1)?

The structure is 38 ft (11.6 m) long with a longest span of 35 ft (10.7 m) and a deck 28 ft wide.

Who owns Back Rd; Old Lemhi over Pratt Creek (#1)?

It is owned by the County Highway Agency.