US Bridges

Ramp I-5 to I-405 over Ramp SR 518 to I-5

Good

King County, Washington · 5.2 N JCT SR 516 · Structure no. 0007401I0000000

Built
1966
59 years old
Condition
Good
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
176 ft
3 main spans
Daily traffic
34,031
2022 count
Owner
State
State Highway Agency

About this bridge

Ramp I-5 to I-405 over Ramp SR 518 to I-5 is a prestressed concrete stringer/multi-beam or girder carrying Ramp I-5 to I-405 over Ramp SR 518 to I-5 in King County, Washington. It was built in 1966, so it is 59 years old, older than the Washington average of 49.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 34,031 vehicles a day, roughly 5% of them trucks, projected to reach 51,735 by 2039. The structure is 176 ft (53.6 m) long and 35 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesRamp I-5 to I-405
CrossesRamp SR 518 to I-5
Location5.2 N JCT SR 516
RouteInterstate 5
CountyKing County
StateWashington
Coordinates47.46247, -122.26533
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment6: Equal to present minimum criteria
Operating rating34.6 US tons
Inventory rating26.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length176 ft (53.6 m)
Longest span68 ft (20.7 m)
Deck width35 ft (10.6 m)
Roadway width31 ft (9.4 m)
Vertical clearance over deck21 ft (6.5 m)

Traffic and service

Average daily traffic34,031 (2022)
Projected traffic51,735 by 2039
Trucks5%
Lanes on structure2
Traffic directionOne-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed1.2 mi (2 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 proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$2.8 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was Ramp I-5 to I-405 over Ramp SR 518 to I-5 built?

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

What condition is Ramp I-5 to I-405 over Ramp SR 518 to I-5 in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in August 2023.

How much traffic does Ramp I-5 to I-405 over Ramp SR 518 to I-5 carry?

About 34,031 vehicles per day (2022 count), of which roughly 5% are trucks.

How long is Ramp I-5 to I-405 over Ramp SR 518 to I-5?

The structure is 176 ft (53.6 m) long with a longest span of 68 ft (20.7 m) and a deck 35 ft wide.

Who owns Ramp I-5 to I-405 over Ramp SR 518 to I-5?

It is owned by the State Highway Agency.