US Bridges

Or 78 (hwy 442) over Silvies SLOUGH(17th Br)

Good

Harney County, Oregon · 5.7 Mi. Se. JCT US 20/395 · Structure no. 06834A442 00570

Built
1971
54 years old
Condition
Good
inspected October 2024
Type
Slab
Prestressed Concrete
Length
31 ft
1 main span
Daily traffic
1,176
2022 count
Owner
State
State Highway Agency

About this bridge

Or 78 (hwy 442) over Silvies SLOUGH(17th Br) is a prestressed concrete slab carrying Or 78 (hwy 442) over Silvies SLOUGH(17th 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 1,176 vehicles a day, roughly 33% of them trucks, projected to reach 1,300 by 2042. The structure is 31 ft (9.4 m) long and 36 ft wide. If it were closed, the detour would be 28 mi (45 km).

CarriesOr 78 (hwy 442)
CrossesSilvies SLOUGH(17th Br)
Location5.7 Mi. Se. JCT US 20/395
RouteState Highway 78
StateOregon
Coordinates43.56425, -118.953
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 protection7 GoodSome minor problems.
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 rating60.4 US tons
Inventory rating46.4 US tons

Structure

Structure typeSlab
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans1
Design loadHS 20
Structure length31 ft (9.4 m)
Longest span30 ft (9.1 m)
Deck width36 ft (11 m)
Roadway width34 ft (10.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,176 (2022)
Projected traffic1,300 by 2042
Trucks33%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed28 mi (45 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(17th Br) built?

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

What condition is Or 78 (hwy 442) over Silvies SLOUGH(17th 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(17th Br) carry?

About 1,176 vehicles per day (2022 count), of which roughly 33% are trucks.

How long is Or 78 (hwy 442) over Silvies SLOUGH(17th Br)?

The structure is 31 ft (9.4 m) long with a longest span of 30 ft (9.1 m) and a deck 36 ft wide.

Who owns Or 78 (hwy 442) over Silvies SLOUGH(17th Br)?

It is owned by the State Highway Agency.