US Bridges

County RD 21 over Cow Creek

Good

Douglas County, Oregon · At Riddle S City Limits · Structure no. 20531 21 503

Built
2008
17 years old
Condition
Good
inspected June 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
358 ft
2 main spans
Daily traffic
5,155
2020 count
Owner
County
County Highway Agency

About this bridge

County RD 21 over Cow Creek is a steel continuous stringer/multi-beam or girder carrying County RD 21 over Cow Creek in Douglas County, Oregon. It was built in 2008, so it is 17 years old, younger than the Oregon average of 49.9 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 5,155 vehicles a day, roughly 7% of them trucks, projected to reach 5,829 by 2025. The structure is 358 ft (109.1 m) long and 51 ft wide. If it were closed, the detour would be 8.1 mi (13 km).

Location

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CarriesCounty RD 21
CrossesCow Creek
LocationAt Riddle S City Limits
RouteCounty Highway A0386
CountyDouglas County
StateOregon
Coordinates42.94726, -123.36294
Functional classRural Major Collector

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation7: Better than present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating46.4 US tons
Inventory rating35.7 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHL 93
Structure length358 ft (109.1 m)
Longest span178 ft (54.3 m)
Deck width51 ft (15.4 m)
Roadway width35 ft (10.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,155 (2020)
Projected traffic5,829 by 2025
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed8.1 mi (13 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was County RD 21 over Cow Creek built?

It was built in 2008, making it 17 years old in 2025.

What condition is County RD 21 over Cow Creek in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in June 2023.

How much traffic does County RD 21 over Cow Creek carry?

About 5,155 vehicles per day (2020 count), of which roughly 7% are trucks.

How long is County RD 21 over Cow Creek?

The structure is 358 ft (109.1 m) long with a longest span of 178 ft (54.3 m) and a deck 51 ft wide.

Who owns County RD 21 over Cow Creek?

It is owned by the County Highway Agency.