US Bridges

HWY 350 over Imnaha River

Fair

Wallowa County, Oregon · In Imnaha · Structure no. 18074 350 02934

Built
1997
28 years old
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
112 ft
1 main span
Daily traffic
215
2022 count
Owner
State
State Highway Agency

About this bridge

HWY 350 over Imnaha River is a steel stringer/multi-beam or girder carrying HWY 350 over Imnaha River in Wallowa County, Oregon. It was built in 1997, so it is 28 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 215 vehicles a day, roughly 36% of them trucks, projected to reach 230 by 2042. The structure is 112 ft (34 m) long and 29 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesHWY 350
CrossesImnaha River
LocationIn Imnaha
RouteState Highway 350
CountyWallowa County
StateOregon
Coordinates45.55935, -116.8341
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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
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 rating89.9 US tons
Inventory rating69.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckClosed grating
Main spans1
Design loadHS 20
Structure length112 ft (34 m)
Longest span110 ft (33.5 m)
Deck width29 ft (8.8 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic215 (2022)
Projected traffic230 by 2042
Trucks36%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed123.7 mi (199 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState 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 HWY 350 over Imnaha River built?

It was built in 1997, making it 28 years old in 2025.

What condition is HWY 350 over Imnaha 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 2024.

How much traffic does HWY 350 over Imnaha River carry?

About 215 vehicles per day (2022 count), of which roughly 36% are trucks.

How long is HWY 350 over Imnaha River?

The structure is 112 ft (34 m) long with a longest span of 110 ft (33.5 m) and a deck 29 ft wide.

Who owns HWY 350 over Imnaha River?

It is owned by the State Highway Agency.