US Bridges

I-5 (hwy 1) over Oregon Slough

Fair

Multnomah County, Oregon · 0.8 MI S of Interstate Br · Structure no. 16526 001 30759

Built
1987
38 years old
Condition
Fair
inspected December 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
1,325 ft
9 main spans
Daily traffic
125,775
2022 count
Owner
State
State Highway Agency

About this bridge

I-5 (hwy 1) over Oregon Slough is a prestressed concrete stringer/multi-beam or girder carrying I-5 (hwy 1) over Oregon Slough in Multnomah County, Oregon. It was built in 1987, so it is 38 years old, younger 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 6 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 125,775 vehicles a day, roughly 9% of them trucks, projected to reach 127,300 by 2042. The structure is 1,325 ft (403.9 m) long and 147 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-5 (hwy 1)
CrossesOregon Slough
Location0.8 MI S of Interstate Br
RouteInterstate 5
CountyMultnomah County
StateOregon
Coordinates45.60767, -122.68143
Functional classUrban Principal Arterial - Interstate

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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionDecember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating49.6 US tons
Inventory rating38.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans9
Design loadHS 25 or greater
Structure length1,325 ft (403.9 m)
Longest span230 ft (70.1 m)
Deck width147 ft (44.9 m)
Roadway width130 ft (39.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic125,775 (2022)
Projected traffic127,300 by 2042
Trucks9%
Lanes on structure8
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesHighway and waterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

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—
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was I-5 (hwy 1) over Oregon Slough built?

It was built in 1987, making it 38 years old in 2025.

What condition is I-5 (hwy 1) over Oregon Slough 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 December 2024.

How much traffic does I-5 (hwy 1) over Oregon Slough carry?

About 125,775 vehicles per day (2022 count), of which roughly 9% are trucks.

How long is I-5 (hwy 1) over Oregon Slough?

The structure is 1,325 ft (403.9 m) long with a longest span of 230 ft (70.1 m) and a deck 147 ft wide.

Who owns I-5 (hwy 1) over Oregon Slough?

It is owned by the State Highway Agency.