US Bridges

45th Ave NE over Thornton Creek

Fair

King County, Washington · 45th Ave NE & NE 97th ST · Structure no. 085598000000000

Built
1949
76 years old
Condition
Fair
inspected August 2023
Type
Slab
Concrete Continuous
Length
43 ft
3 main spans
Daily traffic
2,500
2020 count
Owner
City
City or Municipal Highway Agency

About this bridge

45th Ave NE over Thornton Creek is a concrete continuous slab carrying 45th Ave NE over Thornton Creek in King County, Washington. It was built in 1949, so it is 76 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 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 2,500 vehicles a day, roughly 3% of them trucks, projected to reach 2,700 by 2042. The structure is 43 ft (13.1 m) long and 32 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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Carries45th Ave NE
CrossesThornton Creek
Location45th Ave NE & NE 97th ST
RouteCity Street 1140
CountyKing County
StateWashington
Coordinates47.69913, -122.28006
Functional classUrban 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 inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation6: Equal to present minimum criteria
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating43 US tons
Inventory rating25 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadH 15
Structure length43 ft (13.1 m)
Longest span29 ft (8.8 m)
Deck width32 ft (9.9 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,500 (2020)
Projected traffic2,700 by 2042
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
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 statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$1.9 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was 45th Ave NE over Thornton Creek built?

It was built in 1949, making it 76 years old in 2025.

What condition is 45th Ave NE over Thornton 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 August 2023.

How much traffic does 45th Ave NE over Thornton Creek carry?

About 2,500 vehicles per day (2020 count), of which roughly 3% are trucks.

How long is 45th Ave NE over Thornton Creek?

The structure is 43 ft (13.1 m) long with a longest span of 29 ft (8.8 m) and a deck 32 ft wide.

Who owns 45th Ave NE over Thornton Creek?

It is owned by the City or Municipal Highway Agency.