US Bridges

NE 21st Ave over B-8 over Columbia Slough

Fair

Multnomah County, Oregon · 21st-N of Columbia Blvd · Structure no. 25B08 000

Built
1974
51 years old
Condition
Fair
inspected July 2024
Type
Slab
Prestressed Concrete
Length
129 ft
3 main spans
Daily traffic
1,416
2020 count
Owner
City
City or Municipal Highway Agency

About this bridge

NE 21st Ave over B-8 over Columbia Slough is a prestressed concrete slab carrying NE 21st Ave over B-8 over Columbia Slough in Multnomah County, Oregon. It was built in 1974, so it is 51 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 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 1,416 vehicles a day, roughly 10% of them trucks, projected to reach 1,562 by 2025. The structure is 129 ft (39.3 m) long and 56 ft wide.

Location

Open in Google Maps
CarriesNE 21st Ave
CrossesB-8 over Columbia Slough
Location21st-N of Columbia Blvd
RouteCity Street C0000
CountyMultnomah County
StateOregon
Coordinates45.58119, -122.64387
Functional classUrban Local

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.
Substructure8 Very GoodNo problems noted.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating68 US tons
Inventory rating40 US tons

Structure

Structure typeSlab
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans3
Design loadHS 20
Structure length129 ft (39.3 m)
Longest span42 ft (12.8 m)
Deck width56 ft (17.1 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,416 (2020)
Projected traffic1,562 by 2025
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed—
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$728,000
NavigationNo navigation control on waterway

Frequently asked questions

When was NE 21st Ave over B-8 over Columbia Slough built?

It was built in 1974, making it 51 years old in 2025.

What condition is NE 21st Ave over B-8 over Columbia 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 July 2024.

How much traffic does NE 21st Ave over B-8 over Columbia Slough carry?

About 1,416 vehicles per day (2020 count), of which roughly 10% are trucks.

How long is NE 21st Ave over B-8 over Columbia Slough?

The structure is 129 ft (39.3 m) long with a longest span of 42 ft (12.8 m) and a deck 56 ft wide.

Who owns NE 21st Ave over B-8 over Columbia Slough?

It is owned by the City or Municipal Highway Agency.