US Bridges

S4815;FLNIGAN Crk over Palouse R;nw.Potlatch Br

FairPosted for load

Latah County, Idaho · 0.3 N. 1.0 W. Potlatch · Structure no. 000000000029485

Built
1940
85 years old, rebuilt 1970
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
80 ft
1 main span
Daily traffic
220
2023 count
Owner
Local
Other Local Agency

About this bridge

S4815;FLNIGAN Crk over Palouse R;nw.Potlatch Br is a steel stringer/multi-beam or girder carrying S4815;FLNIGAN Crk over Palouse R;nw.Potlatch Br in Latah County, Idaho. It was built in 1940 and reconstructed in 1970, so it is 85 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 220 vehicles a day, roughly 5% of them trucks, projected to reach 330 by 2042. The structure is 80 ft (24.4 m) long and 30 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

Open in Google Maps
CarriesS4815;FLNIGAN Crk
CrossesPalouse R;nw.Potlatch Br
Location0.3 N. 1.0 W. Potlatch
RouteCounty Highway 4815
CountyLatah County
StateIdaho
Coordinates46.92522, -116.92189
Functional classRural Major Collector

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating31 US tons
Inventory rating18 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadH 15
Structure length80 ft (24.4 m)
Longest span75 ft (22.9 m)
Deck width30 ft (9.2 m)
Roadway width29 ft (8.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic220 (2023)
Projected traffic330 by 2042
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerOther Local Agency
Maintained byOther Local Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$798,000 (2019 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was S4815;FLNIGAN Crk over Palouse R;nw.Potlatch Br built?

It was built in 1940, making it 85 years old in 2025. It was reconstructed in 1970.

What condition is S4815;FLNIGAN Crk over Palouse R;nw.Potlatch Br 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 June 2023.

How much traffic does S4815;FLNIGAN Crk over Palouse R;nw.Potlatch Br carry?

About 220 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is S4815;FLNIGAN Crk over Palouse R;nw.Potlatch Br?

The structure is 80 ft (24.4 m) long with a longest span of 75 ft (22.9 m) and a deck 30 ft wide.

Who owns S4815;FLNIGAN Crk over Palouse R;nw.Potlatch Br?

It is owned by the Other Local Agency.