US Bridges

21st ST SE over Mill Creek

Fair

Marion County, Oregon · 100 Block · Structure no. 470240000

Built
1960
65 years old
Condition
Fair
inspected August 2023
Type
Slab
Concrete Continuous
Length
92 ft
5 main spans
Daily traffic
4,484
2020 count
Owner
City
City or Municipal Highway Agency

About this bridge

21st ST SE over Mill Creek is a concrete continuous slab carrying 21st ST SE over Mill Creek in Marion County, Oregon. It was built in 1960, so it is 65 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 4,484 vehicles a day, roughly 3% of them trucks, projected to reach 5,039 by 2025. The structure is 92 ft (28 m) long and 44 ft wide.

Location

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Carries21st ST SE
CrossesMill Creek
Location100 Block
RouteCity Street C0000
CountyMarion County
StateOregon
Coordinates44.9336, -123.01648
Functional classUrban Collector

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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
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
Waterway adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating43 US tons
Inventory rating26 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans5
Design loadHS 20
Structure length92 ft (28 m)
Longest span18 ft (5.5 m)
Deck width44 ft (13.4 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,484 (2020)
Projected traffic5,039 by 2025
Trucks3%
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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was 21st ST SE over Mill Creek built?

It was built in 1960, making it 65 years old in 2025.

What condition is 21st ST SE over Mill Creek 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 August 2023.

How much traffic does 21st ST SE over Mill Creek carry?

About 4,484 vehicles per day (2020 count), of which roughly 3% are trucks.

How long is 21st ST SE over Mill Creek?

The structure is 92 ft (28 m) long with a longest span of 18 ft (5.5 m) and a deck 44 ft wide.

Who owns 21st ST SE over Mill Creek?

It is owned by the City or Municipal Highway Agency.