US Bridges

Road over Zigzag River

FairPosted for load

Clackamas County, Oregon · S-15 T-3S R-8E Wm · Structure no. 060609000001446

Built
1952
73 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
76 ft
3 main spans
Daily traffic
50
Owner
Federal
U.S. Forest Service

About this bridge

Road over Zigzag River is a wood or timber stringer/multi-beam or girder carrying Road over Zigzag River in Clackamas County, Oregon. It was built in 1952, so it is 73 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 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. Its operating status is: posted for load restriction.

It carries about 50 vehicles a day, projected to reach 75 by 2045. The structure is 76 ft (23.3 m) long and 18 ft wide. If it were closed, the detour would be 620.7 mi (999 km).

Location

Open in Google Maps
CarriesRoad
CrossesZigzag River
LocationS-15 T-3S R-8E Wm
RouteFederal Lands Road 26390
CountyClackamas County
StateOregon
Coordinates45.31389, -121.8165
Functional classRural Local

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating23 US tons
Inventory rating16 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans3
Design loadUnknown
Structure length76 ft (23.3 m)
Longest span29 ft (8.8 m)
Deck width18 ft (5.5 m)
Roadway width16 ft (4.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic50 (—)
Projected traffic75 by 2045
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed620.7 mi (999 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerU.S. Forest Service
Maintained byU.S. Forest Service
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Road over Zigzag River built?

It was built in 1952, making it 73 years old in 2025.

What condition is Road over Zigzag 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 August 2024.

How much traffic does Road over Zigzag River carry?

About 50 vehicles per day (latest count).

How long is Road over Zigzag River?

The structure is 76 ft (23.3 m) long with a longest span of 29 ft (8.8 m) and a deck 18 ft wide.

Who owns Road over Zigzag River?

It is owned by the U.S. Forest Service.