US Bridges

SR 99 over SR 99 NB SR 99 Nb/Ramp

Good

King County, Washington · 5.5 N JCT SR 509 · Structure no. 0018549A0000000

Built
2015
10 years old
Condition
Good
inspected August 2023
Type
Box Beam or Girders - Multiple
Prestressed Concrete Continuous
Length
179 ft
2 main spans
Daily traffic
15,919
2019 count
Owner
State
State Highway Agency

About this bridge

SR 99 over SR 99 NB SR 99 Nb/Ramp is a prestressed concrete continuous box beam or girders - multiple carrying SR 99 over SR 99 NB SR 99 Nb/Ramp in King County, Washington. It was built in 2015, so it is 10 years old, younger 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 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 15,919 vehicles a day, roughly 4% of them trucks, projected to reach 22,477 by 2039. The structure is 179 ft (54.6 m) long and 84 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesSR 99
CrossesSR 99 NB SR 99 Nb/Ramp
Location5.5 N JCT SR 509
RouteState Highway 99
CountyKing County
StateWashington
Coordinates47.6225, -122.34377
Functional classUrban Principal Arterial - Other Freeway or Expressway

Condition and inspection

Good

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

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation8: Equal to present desirable criteria
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating46.4 US tons
Inventory rating35.7 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHL 93
Structure length179 ft (54.6 m)
Longest span104 ft (31.7 m)
Deck width84 ft (25.6 m)
Roadway width81 ft (24.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic15,919 (2019)
Projected traffic22,477 by 2039
Trucks4%
Lanes on structure5
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a toll road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$7.1 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 99 over SR 99 NB SR 99 Nb/Ramp built?

It was built in 2015, making it 10 years old in 2025.

What condition is SR 99 over SR 99 NB SR 99 Nb/Ramp 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 SR 99 over SR 99 NB SR 99 Nb/Ramp carry?

About 15,919 vehicles per day (2019 count), of which roughly 4% are trucks.

How long is SR 99 over SR 99 NB SR 99 Nb/Ramp?

The structure is 179 ft (54.6 m) long with a longest span of 104 ft (31.7 m) and a deck 84 ft wide.

Who owns SR 99 over SR 99 NB SR 99 Nb/Ramp?

It is owned by the State Highway Agency.