US Bridges

Cottom Lane over Lemhi River

FairPosted for load

Lemhi County, Idaho · 7.2 S. 7.1 E. Lemhi · Structure no. 000000000032720

Built
1950
75 years old, rebuilt 1968
Condition
Fair
inspected July 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
41 ft
1 main span
Daily traffic
70
2023 count
Owner
County
County Highway Agency

About this bridge

Cottom Lane over Lemhi River is a wood or timber stringer/multi-beam or girder carrying Cottom Lane over Lemhi River in Lemhi County, Idaho. It was built in 1950 and reconstructed in 1968, so it is 75 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 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. Its operating status is: posted for load restriction.

It carries about 70 vehicles a day, roughly 10% of them trucks, projected to reach 105 by 2039. The structure is 41 ft (12.5 m) long and 25 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesCottom Lane
CrossesLemhi River
Location7.2 S. 7.1 E. Lemhi
RouteCounty Highway 0
CountyLemhi County
StateIdaho
Coordinates44.74911, -113.47578
Functional classRural Local

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation4: Meets minimum tolerable limits to be 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 alignment8: Equal to present desirable criteria
Operating rating28 US tons
Inventory rating17 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadH 15
Structure length41 ft (12.5 m)
Longest span39 ft (11.9 m)
Deck width25 ft (7.7 m)
Roadway width23 ft (7.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic70 (2023)
Projected traffic105 by 2039
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$416,000 (2018 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Cottom Lane over Lemhi River built?

It was built in 1950, making it 75 years old in 2025. It was reconstructed in 1968.

What condition is Cottom Lane over Lemhi 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 July 2023.

How much traffic does Cottom Lane over Lemhi River carry?

About 70 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is Cottom Lane over Lemhi River?

The structure is 41 ft (12.5 m) long with a longest span of 39 ft (11.9 m) and a deck 25 ft wide.

Who owns Cottom Lane over Lemhi River?

It is owned by the County Highway Agency.