US Bridges

SH 21 over Stanley Lake Creek

Fair

Custer County, Idaho · 4.4 W. Stanley · Structure no. 000000000012960

Built
1966
59 years old
Condition
Fair
inspected July 2022
Type
Tee Beam
Concrete Continuous
Length
90 ft
3 main spans
Daily traffic
620
2023 count
Owner
State
State Highway Agency

About this bridge

SH 21 over Stanley Lake Creek is a concrete continuous tee beam carrying SH 21 over Stanley Lake Creek in Custer County, Idaho. It was built in 1966, so it is 59 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.

It carries about 620 vehicles a day, roughly 22% of them trucks, projected to reach 930 by 2042. The structure is 90 ft (27.4 m) long and 33 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

CarriesSH 21
CrossesStanley Lake Creek
Location4.4 W. Stanley
RouteState Highway 21
StateIdaho
Coordinates44.25342, -115.00653
Functional classRural Minor Arterial

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 inspectionJuly 2022
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
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 rating60 US tons
Inventory rating36 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length90 ft (27.4 m)
Longest span57 ft (17.4 m)
Deck width33 ft (10.1 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic620 (2023)
Projected traffic930 by 2042
Trucks22%
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 21 over Stanley Lake Creek built?

It was built in 1966, making it 59 years old in 2025.

What condition is SH 21 over Stanley Lake Creek 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 2022.

How much traffic does SH 21 over Stanley Lake Creek carry?

About 620 vehicles per day (2023 count), of which roughly 22% are trucks.

How long is SH 21 over Stanley Lake Creek?

The structure is 90 ft (27.4 m) long with a longest span of 57 ft (17.4 m) and a deck 33 ft wide.

Who owns SH 21 over Stanley Lake Creek?

It is owned by the State Highway Agency.