US101 (hwy 9) over Half Viaduct

Tillamook County, Oregon · rated Good in the 2025 National Bridge Inventory

United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled August 20, 2026

• US101 (hwy 9) over Half Viaduct in Tillamook County, Oregon, is rated in good condition in the 2025 National Bridge Inventory (as of August 20, 2026).
• Its lowest-rated component is the deck, rated 8 (very good condition) on the 0-9 scale.
• It was built in 1940, making it 85 years old at the 2025 inventory.
• It carries about 5,743 vehicles a day (traffic count year 2022).
• Its listed owner is the state highway agency.
• It is one of 68 of the 228 inventoried bridges in Tillamook County rated good (29.8%); 15 (6.6%) are rated poor.
• A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.

View this bridge on a map → (45.7443, -123.9598)

Component ratings

Bridge details

Source: FHWA National Bridge Inventory, 2025 data as reported by the Oregon department of transportation.

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Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.