US Bridges

SR 99 over I-5

Fair

Snohomish County, Washington · JCT I-5 · Structure no. 0007116B0000000

Built
1963
62 years old
Condition
Fair
inspected November 2023
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
341 ft
4 main spans
Daily traffic
19,534
2023 count
Owner
State
State Highway Agency

About this bridge

SR 99 over I-5 is a concrete continuous box beam or girders - multiple carrying SR 99 over I-5 in Snohomish County, Washington. It was built in 1963, so it is 62 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.

It carries about 19,534 vehicles a day, roughly 3% of them trucks, projected to reach 29,811 by 2039. The structure is 341 ft (104 m) long and 36 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesSR 99
CrossesI-5
LocationJCT I-5
RouteState Highway 99
CountySnohomish County
StateWashington
Coordinates47.91506, -122.20892
Functional classUrban Other Principal Arterial

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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionNovember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment6: Equal to present minimum criteria
Operating rating79 US tons
Inventory rating46 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length341 ft (104 m)
Longest span93 ft (28.3 m)
Deck width36 ft (11 m)
Roadway width31 ft (9.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic19,534 (2023)
Projected traffic29,811 by 2039
Trucks3%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.9 mi (3 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$5.5 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 99 over I-5 built?

It was built in 1963, making it 62 years old in 2025.

What condition is SR 99 over I-5 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 November 2023.

How much traffic does SR 99 over I-5 carry?

About 19,534 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is SR 99 over I-5?

The structure is 341 ft (104 m) long with a longest span of 93 ft (28.3 m) and a deck 36 ft wide.

Who owns SR 99 over I-5?

It is owned by the State Highway Agency.