Structure 1951 009 04086 · Tillamook County, OR

Us101 (hwy 9) over Half Viaduct

Carries Us101 (hwy 9) over Half Viaduct, 023 Mi N Manzanita.

Overall conditionFair

Set by its lowest-rated component: Substructure at 6 of 9.

How ratings work
Deck8/9 · Very Good
Superstructure8/9 · Very Good
Substructuresets the rating6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT375 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 8/9Superstructure 8/9Substructure 6/9 · sets the rating

375 ft end to end, longest span 15 ft: about 5 semi-trucks nose to tail. Lengths and the semi-truck on the deck are drawn to the same scale. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a tee-beam bridge.

Built194086 years old
Length375.0 ft114.3 m
Daily traffic5,743counted 2022
Last inspectedOctober 2024every 24 months

Location

StateOregon
CountyTillamook
Location023 Mi N Manzanita
CarriesUs101 (hwy 9)
CrossesHalf Viaduct
Coordinates45.74187, -123.95450

Physical Characteristics

MaterialConcrete Continuous
DesignTee Beam
Total Length375.0 ft (114.3 m)
Max Span15.1 ft (4.6 m)
Deck Width22.6 ft (6.9 m)
Deck Area788.7 sq m
Main Spans25
Year Built1940

Traffic

Avg Daily Traffic5,743 (2022)
Truck Traffic12%
Lanes On Bridge2

Inspection & Ownership

Last InspectionOctober 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is eligible for the National Register
Scour CriticalNot applicable
Structure Number01951 009 04086

How Bridge Ratings Work

Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."

0Failed
1Imminent failure
2Critical
3Serious
4Poor
5Fair
6Satisfactory
7Good
8Very good
9Excellent
Good · lowest component 7–9
Fair · lowest component 5–6
Poor · lowest component 0–4

A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.

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