US Bridges

Sterling Highway over Ninilchik River

Fair

Kenai Peninsula Borough, Alaska · Mile Point 95.7 · Structure no. 0669

Built
1965
60 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
159 ft
3 main spans
Daily traffic
2,420
2020 count
Owner
State
State Highway Agency

About this bridge

Sterling Highway over Ninilchik River is a steel continuous stringer/multi-beam or girder carrying Sterling Highway over Ninilchik River in Kenai Peninsula Borough, Alaska. It was built in 1965, so it is 60 years old, older than the Alaska average of 35.9 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 2,420 vehicles a day, roughly 11% of them trucks, projected to reach 2,760 by 2039. The structure is 159 ft (48.5 m) long and 34 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

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CarriesSterling Highway
CrossesNinilchik River
LocationMile Point 95.7
RouteState Highway 21
CountyKenai Peninsula Borough
StateAlaska
Coordinates60.04778, -151.65833
Functional classRural Principal Arterial - Other

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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating69.4 US tons
Inventory rating32 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadH 20
Structure length159 ft (48.5 m)
Longest span60 ft (18.3 m)
Deck width34 ft (10.4 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,420 (2020)
Projected traffic2,760 by 2039
Trucks11%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Sterling Highway over Ninilchik River built?

It was built in 1965, making it 60 years old in 2025.

What condition is Sterling Highway over Ninilchik 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 August 2023.

How much traffic does Sterling Highway over Ninilchik River carry?

About 2,420 vehicles per day (2020 count), of which roughly 11% are trucks.

How long is Sterling Highway over Ninilchik River?

The structure is 159 ft (48.5 m) long with a longest span of 60 ft (18.3 m) and a deck 34 ft wide.

Who owns Sterling Highway over Ninilchik River?

It is owned by the State Highway Agency.