US Bridges

NB SR 16 over Tacoma Narrows

Fair

Pierce County, Washington · 5.1 N JCT I-5 · Structure no. 0003418A0000000

Built
1949
76 years old
Condition
Fair
inspected July 2023
Type
Suspension
Steel Continuous
Length
5,978 ft
3 main spans
Daily traffic
44,741
2023 count
Owner
State
State Highway Agency

About this bridge

NB SR 16 over Tacoma Narrows is a steel continuous suspension carrying NB SR 16 over Tacoma Narrows in Pierce County, Washington. It was built in 1949, so it is 76 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 44,741 vehicles a day, roughly 5% of them trucks, projected to reach 62,831 by 2039. The structure is 5,978 ft (1,822.1 m) long and 54 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesNB SR 16
CrossesTacoma Narrows
Location5.1 N JCT I-5
RouteState Highway 16
CountyPierce County
StateWashington
Coordinates47.26472, -122.54603
Functional classUrban Principal Arterial - Other Freeway or Expressway

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating22.5 US tons
Inventory rating17.2 US tons

Structure

Structure typeSuspension
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3 (+10 approach)
Design loadUnknown
Structure length5,978 ft (1,822.1 m)
Longest span2,800 ft (853.4 m)
Deck width54 ft (16.4 m)
Roadway width46 ft (14.1 m)
Vertical clearance over deck82 ft (25 m)

Traffic and service

Average daily traffic44,741 (2023)
Projected traffic62,831 by 2039
Trucks5%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesRailroad and waterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkSTRAHNET connector

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusEligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$119.3 million (2022 estimate)
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was NB SR 16 over Tacoma Narrows built?

It was built in 1949, making it 76 years old in 2025.

What condition is NB SR 16 over Tacoma Narrows 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 July 2023.

How much traffic does NB SR 16 over Tacoma Narrows carry?

About 44,741 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is NB SR 16 over Tacoma Narrows?

The structure is 5,978 ft (1,822.1 m) long with a longest span of 2,800 ft (853.4 m) and a deck 54 ft wide.

Who owns NB SR 16 over Tacoma Narrows?

It is owned by the State Highway Agency.