US Bridges

I-405 over Coal Creek Parkway SE

Fair

King County, Washington · 4.8 N JCT SR 900 · Structure no. 0007623D0000000

Built
1965
60 years old, rebuilt 1986
Condition
Fair
inspected April 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
224 ft
3 main spans
Daily traffic
71,797
2023 count
Owner
State
State Highway Agency

About this bridge

I-405 over Coal Creek Parkway SE is a prestressed concrete stringer/multi-beam or girder carrying I-405 over Coal Creek Parkway SE in King County, Washington. It was built in 1965 and reconstructed in 1986, so it is 60 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 71,797 vehicles a day, roughly 6% of them trucks, projected to reach 103,444 by 2039. The structure is 224 ft (68.3 m) long and 47 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

CarriesI-405
CrossesCoal Creek Parkway SE
Location4.8 N JCT SR 900
RouteInterstate 405
Coordinates47.56769, -122.18014
Functional classUrban Principal Arterial - Interstate

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.
Last inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating61.9 US tons
Inventory rating36 US tons

Structure

MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length224 ft (68.3 m)
Longest span90 ft (27.4 m)
Deck width47 ft (14.2 m)
Roadway width44 ft (13.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic71,797 (2023)
Projected traffic103,444 by 2039
Trucks6%
Lanes on structure3
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$4.8 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-405 over Coal Creek Parkway SE built?

It was built in 1965, making it 60 years old in 2025. It was reconstructed in 1986.

What condition is I-405 over Coal Creek Parkway SE 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 April 2024.

How much traffic does I-405 over Coal Creek Parkway SE carry?

About 71,797 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is I-405 over Coal Creek Parkway SE?

The structure is 224 ft (68.3 m) long with a longest span of 90 ft (27.4 m) and a deck 47 ft wide.

Who owns I-405 over Coal Creek Parkway SE?

It is owned by the State Highway Agency.