US Bridges

Upper Imnaha Road over Imnaha River

Fair

Wallowa County, Oregon · 19.3 MI S of HWY 350 · Structure no. 20448 727 01927

Built
2006
19 years old
Condition
Fair
inspected September 2024
Type
Tee Beam
Prestressed Concrete
Length
135 ft
1 main span
Daily traffic
70
2020 count
Owner
County
County Highway Agency

About this bridge

Upper Imnaha Road over Imnaha River is a prestressed concrete tee beam carrying Upper Imnaha Road over Imnaha River in Wallowa County, Oregon. It was built in 2006, so it is 19 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 70 vehicles a day, roughly 5% of them trucks, projected to reach 85 by 2025. The structure is 135 ft (41.1 m) long and 31 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

CarriesUpper Imnaha Road
CrossesImnaha River
Location19.3 MI S of HWY 350
RouteCounty Highway 0
StateOregon
Coordinates45.3166, -116.80496
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
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating88 US tons
Inventory rating53 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans1
Design loadHS 25 or greater
Structure length135 ft (41.1 m)
Longest span133 ft (40.5 m)
Deck width31 ft (9.6 m)
Roadway width28 ft (8.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic70 (2020)
Projected traffic85 by 2025
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 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 Upper Imnaha Road over Imnaha River built?

It was built in 2006, making it 19 years old in 2025.

What condition is Upper Imnaha Road 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 September 2024.

How much traffic does Upper Imnaha Road over Imnaha River carry?

About 70 vehicles per day (2020 count), of which roughly 5% are trucks.

How long is Upper Imnaha Road over Imnaha River?

The structure is 135 ft (41.1 m) long with a longest span of 133 ft (40.5 m) and a deck 31 ft wide.

Who owns Upper Imnaha Road over Imnaha River?

It is owned by the County Highway Agency.