US Bridges

SR 161 over I-5

Fair

King County, Washington · 1.7 N Pierce CO · Structure no. 0006094D0000000

Built
1959
66 years old, rebuilt 1998
Condition
Fair
inspected October 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
406 ft
5 main spans
Daily traffic
31,811
2023 count
Owner
State
State Highway Agency

About this bridge

SR 161 over I-5 is a prestressed concrete stringer/multi-beam or girder carrying SR 161 over I-5 in King County, Washington. It was built in 1959 and reconstructed in 1998, so it is 66 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 31,811 vehicles a day, roughly 4% of them trucks, projected to reach 43,500 by 2039. The structure is 406 ft (123.7 m) long and 78 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesSR 161
CrossesI-5
Location1.7 N Pierce CO
RouteState Highway 161
CountyKing County
StateWashington
Coordinates47.27864, -122.31033
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
Deck7 GoodSome minor problems.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating63.9 US tons
Inventory rating37 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans5
Design loadHS 20
Structure length406 ft (123.7 m)
Longest span91 ft (27.6 m)
Deck width78 ft (23.8 m)
Roadway width62 ft (18.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic31,811 (2023)
Projected traffic43,500 by 2039
Trucks4%
Lanes on structure5
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesHighway
Detour if closed3.7 mi (6 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$12.3 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 161 over I-5 built?

It was built in 1959, making it 66 years old in 2025. It was reconstructed in 1998.

What condition is SR 161 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 October 2024.

How much traffic does SR 161 over I-5 carry?

About 31,811 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is SR 161 over I-5?

The structure is 406 ft (123.7 m) long with a longest span of 91 ft (27.6 m) and a deck 78 ft wide.

Who owns SR 161 over I-5?

It is owned by the State Highway Agency.