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Old Monte Rio Road over Hillside

Sonoma County, California · rated Fair in the 2025 National Bridge Inventory

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

Old Monte Rio Road over Hillside in Sonoma County, California, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the superstructure, rated 6 (satisfactory condition) on the 0-9 scale.
It was built in 2012, making it 13 years old at the 2025 inventory.
It carries about 100 vehicles a day (traffic count year 2015).
Its listed owner is the county highway agency.
It is one of 441 of the 611 inventoried bridges in Sonoma County rated fair (72.2%); 32 (5.2%) are rated poor.
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.

Component ratings


Structure	Steel stringer or multi-beam girder
Length	about 154 ft
Location	Btwn Santa Rosa & Duncan
NBI structure number	20C0573
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
US Highway 101 over College Avenue	2009	136,500	Fair
U.S. Route 101 over Future Rainier Avenue	2022	103,000	Fair
US Highway 101 over 3RD St 4TH St & 5TH St	1968	96,000	Fair
US Highway 101 over Ninth Street	1968	96,000	Fair
U.S. Highway 101 over Santa Rosa Creek	2009	96,000	Fair
U.S. Highway 101 over Sixth Street	2009	96,000	Fair