US Bridges

Or 99W(HWY 91)NB over Tualatin River

Fair

Washington County, Oregon · 0.5 MI S of King City Cc · Structure no. 01417N01W 01218

Built
1955
70 years old
Condition
Fair
inspected February 2024
Type
Girder and Floorbeam System
Concrete Continuous
Length
463 ft
7 main spans
Daily traffic
14,983
2022 count
Owner
State
State Highway Agency

About this bridge

Or 99W(HWY 91)NB over Tualatin River is a concrete continuous girder and floorbeam system carrying Or 99W(HWY 91)NB over Tualatin River in Washington County, Oregon. It was built in 1955, so it is 70 years old, older than the Oregon average of 49.9 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 14,983 vehicles a day, roughly 3% of them trucks, projected to reach 17,500 by 2042. The structure is 463 ft (141.2 m) long and 37 ft wide.

Location

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CarriesOr 99W(HWY 91)NB
CrossesTualatin River
Location0.5 MI S of King City Cc
RouteState Highway 99
CountyWashington County
StateOregon
Coordinates45.39413, -122.79898
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionFebruary 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating31.1 US tons
Inventory rating23.9 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans7
Design loadHS 20
Structure length463 ft (141.2 m)
Longest span100 ft (30.5 m)
Deck width37 ft (11.3 m)
Roadway width30 ft (9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic14,983 (2022)
Projected traffic17,500 by 2042
Trucks3%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed—
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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Or 99W(HWY 91)NB over Tualatin River built?

It was built in 1955, making it 70 years old in 2025.

What condition is Or 99W(HWY 91)NB over Tualatin River 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 February 2024.

How much traffic does Or 99W(HWY 91)NB over Tualatin River carry?

About 14,983 vehicles per day (2022 count), of which roughly 3% are trucks.

How long is Or 99W(HWY 91)NB over Tualatin River?

The structure is 463 ft (141.2 m) long with a longest span of 100 ft (30.5 m) and a deck 37 ft wide.

Who owns Or 99W(HWY 91)NB over Tualatin River?

It is owned by the State Highway Agency.