SR 508 over Alder Creek

Lewis County, Washington · rated Fair in the 2025 National Bridge Inventory

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

• SR 508 over Alder Creek in Lewis County, Washington, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
• Its lowest-rated component is the substructure, rated 5 (fair condition) on the 0-9 scale.
• It was built in 1937, making it 88 years old at the 2025 inventory.
• It carries about 1,200 vehicles a day (traffic count year 2023).
• Its listed owner is the state highway agency.
• It is one of 194 of the 420 inventoried bridges in Lewis County rated fair (46.2%); 17 (4.0%) are rated poor.
• Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
• Its condition class and component ratings are unchanged from the 2024 inventory.
• Its most recent inspection on record is dated February 2024, on a 24-month routine inspection cycle.
• It is coded scour critical (NBI item 113 = 3): scour critical: foundations unstable for the assessed or calculated scour.
• A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.

View this bridge on a map → (46.60428, -122.45108)

Component ratings

Bridge details

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

Busiest bridges in Lewis County

All bridges nearby: Lewis County, WA bridge conditions · every bridge in Lewis County · Washington bridges.

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