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State Route 1 over Alder Creek

Mendocino County, California · rated Good in the 2025 National Bridge Inventory

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

State Route 1 over Alder Creek in Mendocino County, California, is rated in good condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the deck, rated 7 (good condition) on the 0-9 scale.
It was built in 1947, making it 78 years old at the 2025 inventory.
It carries about 1,800 vehicles a day (traffic count year 2009).
Its listed owner is the state highway agency.
It is one of 124 of the 356 inventoried bridges in Mendocino County rated good (34.8%); 27 (7.6%) 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.

Component ratings


Structure	Continuous steel stringer or multi-beam girder
Length	about 124 ft
Location	01-men-001-22.73
NBI structure number	10 0116
Condition class	Good

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

Bridge	Built	Vehicles/day	Condition
State Route 1 over Pudding Creek	1959	23,950	Good
State Route 001 over Noyo River & Harbor Dr	2005	23,950	Good
U.S. Highway 101 over Austin Creek	1964	20,900	Good
North State St over Forsythe Creek	1949	20,200	Fair
U.S. Highway 101 over Ncrra/nwp RR	1957	19,000	Fair
U.S. Highway 101 over Baker Creek	1971	19,000	Good