US Bridges

10th Avenue NW over Side Hill Ravine

FairPosted for load

King County, Washington · 0.1 MI W of NW Innis Ard · Structure no. 081372000000000

Built
1931
94 years old
Condition
Fair
inspected June 2024
Type
Slab
Concrete Continuous
Length
312 ft
10 main spans
Daily traffic
730
2019 count
Owner
City
City or Municipal Highway Agency

About this bridge

10th Avenue NW over Side Hill Ravine is a concrete continuous slab carrying 10th Avenue NW over Side Hill Ravine in King County, Washington. It was built in 1931, so it is 94 years old, older than the Washington average of 49.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 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 730 vehicles a day, roughly 4% of them trucks, projected to reach 850 by 2039. The structure is 312 ft (95.1 m) long and 22 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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Carries10th Avenue NW
CrossesSide Hill Ravine
Location0.1 MI W of NW Innis Ard
RouteCounty Highway 1169
CountyKing County
StateWashington
Coordinates47.75194, -122.37258
Functional classUrban 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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJune 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourBridge not over waterway
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Approach roadway alignment6: Equal to present minimum criteria
Operating rating27.1 US tons
Inventory rating16.4 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans10
Design loadHS 15
Structure length312 ft (95.1 m)
Longest span30 ft (9.1 m)
Deck width22 ft (6.7 m)
Roadway width20 ft (6.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic730 (2019)
Projected traffic850 by 2039
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesOther
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$11.6 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was 10th Avenue NW over Side Hill Ravine built?

It was built in 1931, making it 94 years old in 2025.

What condition is 10th Avenue NW over Side Hill Ravine 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 2024.

How much traffic does 10th Avenue NW over Side Hill Ravine carry?

About 730 vehicles per day (2019 count), of which roughly 4% are trucks.

How long is 10th Avenue NW over Side Hill Ravine?

The structure is 312 ft (95.1 m) long with a longest span of 30 ft (9.1 m) and a deck 22 ft wide.

Who owns 10th Avenue NW over Side Hill Ravine?

It is owned by the City or Municipal Highway Agency.