US Bridges

First Ave over North Santiam River

Fair

Linn County, Oregon · In Mill City · Structure no. 02058 162C03029

Built
1934
91 years old, rebuilt 1960
Condition
Fair
inspected July 2023
Type
Truss - Thru
Steel
Length
362 ft
1 main span
Daily traffic
6,500
2021 count
Owner
County
County Highway Agency

About this bridge

First Ave over North Santiam River is a steel truss - thru carrying First Ave over North Santiam River in Linn County, Oregon. It was built in 1934 and reconstructed in 1960, so it is 91 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 6,500 vehicles a day, roughly 25% of them trucks, projected to reach 6,900 by 2041. The structure is 362 ft (110.3 m) long and 33 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

Open in Google Maps
CarriesFirst Ave
CrossesNorth Santiam River
LocationIn Mill City
RouteCounty Highway C0000
CountyLinn County
StateOregon
Coordinates44.75483, -122.47754
Functional classRural Major 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.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating26.8 US tons
Inventory rating20.7 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckConcrete, cast-in-place
Main spans1 (+5 approach)
Design loadH 15
Structure length362 ft (110.3 m)
Longest span200 ft (61 m)
Deck width33 ft (10.1 m)
Roadway width23 ft (7.1 m)
Vertical clearance over deck14 ft (4.1 m)

Traffic and service

Average daily traffic6,500 (2021)
Projected traffic6,900 by 2041
Trucks25%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
Work proposedWidening of existing bridge without deck rehabilitation
Estimated improvement cost$1.9 million
NavigationNo navigation control on waterway

Frequently asked questions

When was First Ave over North Santiam River built?

It was built in 1934, making it 91 years old in 2025. It was reconstructed in 1960.

What condition is First Ave over North Santiam River 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 2023.

How much traffic does First Ave over North Santiam River carry?

About 6,500 vehicles per day (2021 count), of which roughly 25% are trucks.

How long is First Ave over North Santiam River?

The structure is 362 ft (110.3 m) long with a longest span of 200 ft (61 m) and a deck 33 ft wide.

Who owns First Ave over North Santiam River?

It is owned by the County Highway Agency.