US Bridges

Or 78 (hwy 442) over Silvies SLOUGH(6th Br)

Good

Harney County, Oregon · 1.3 Mi. E. Jct. US 20/395 · Structure no. 03584A442 00129

Built
1971
54 years old
Condition
Good
inspected October 2024
Type
Slab
Prestressed Concrete
Length
51 ft
1 main span
Daily traffic
1,729
2022 count
Owner
State
State Highway Agency

About this bridge

Or 78 (hwy 442) over Silvies SLOUGH(6th Br) is a prestressed concrete slab carrying Or 78 (hwy 442) over Silvies SLOUGH(6th Br) in Harney County, Oregon. It was built in 1971, so it is 54 years old, older 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 1,729 vehicles a day, roughly 37% of them trucks, projected to reach 1,900 by 2042. The structure is 51 ft (15.5 m) long and 36 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

CarriesOr 78 (hwy 442)
CrossesSilvies SLOUGH(6th Br)
Location1.3 Mi. E. Jct. US 20/395
RouteState Highway 78
StateOregon
Coordinates43.58579, -119.02887
Functional classRural Minor Arterial

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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating41.8 US tons
Inventory rating32.2 US tons

Structure

Structure typeSlab
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans1
Design loadHS 20
Structure length51 ft (15.5 m)
Longest span50 ft (15.2 m)
Deck width36 ft (11 m)
Roadway width34 ft (10.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,729 (2022)
Projected traffic1,900 by 2042
Trucks37%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 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 Or 78 (hwy 442) over Silvies SLOUGH(6th Br) built?

It was built in 1971, making it 54 years old in 2025.

What condition is Or 78 (hwy 442) over Silvies SLOUGH(6th Br) 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 October 2024.

How much traffic does Or 78 (hwy 442) over Silvies SLOUGH(6th Br) carry?

About 1,729 vehicles per day (2022 count), of which roughly 37% are trucks.

How long is Or 78 (hwy 442) over Silvies SLOUGH(6th Br)?

The structure is 51 ft (15.5 m) long with a longest span of 50 ft (15.2 m) and a deck 36 ft wide.

Who owns Or 78 (hwy 442) over Silvies SLOUGH(6th Br)?

It is owned by the State Highway Agency.