US Bridges

Middle Ridge Rd. over Oak CR

Fair

Linn County, Oregon · 003 MI S CR 737 · Structure no. 11941A073800034

Built
1979
46 years old
Condition
Fair
inspected June 2024
Type
Slab
Prestressed Concrete
Length
40 ft
1 main span
Daily traffic
299
2021 count
Owner
County
County Highway Agency

About this bridge

Middle Ridge Rd. over Oak CR is a prestressed concrete slab carrying Middle Ridge Rd. over Oak CR in Linn County, Oregon. It was built in 1979, so it is 46 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 299 vehicles a day, roughly 10% of them trucks, projected to reach 422 by 2041. The structure is 40 ft (12.2 m) long and 28 ft wide. If it were closed, the detour would be 14.9 mi (24 km).

Location

Open in Google Maps
CarriesMiddle Ridge Rd.
CrossesOak CR
Location003 MI S CR 737
RouteCounty Highway C0738
CountyLinn County
StateOregon
Coordinates44.48002, -122.87618
Functional classRural 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
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJune 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating70 US tons
Inventory rating53.9 US tons

Structure

Structure typeSlab
MaterialPrestressed Concrete
DeckOther
Main spans1
Design loadHS 20
Structure length40 ft (12.2 m)
Longest span39 ft (11.9 m)
Deck width28 ft (8.6 m)
Roadway width26 ft (8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic299 (2021)
Projected traffic422 by 2041
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed14.9 mi (24 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty 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 Middle Ridge Rd. over Oak CR built?

It was built in 1979, making it 46 years old in 2025.

What condition is Middle Ridge Rd. over Oak CR 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 June 2024.

How much traffic does Middle Ridge Rd. over Oak CR carry?

About 299 vehicles per day (2021 count), of which roughly 10% are trucks.

How long is Middle Ridge Rd. over Oak CR?

The structure is 40 ft (12.2 m) long with a longest span of 39 ft (11.9 m) and a deck 28 ft wide.

Who owns Middle Ridge Rd. over Oak CR?

It is owned by the County Highway Agency.