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State Route 20 over Interstate 5

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

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

State Route 20 over Interstate 5 in Colusa 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 1971, making it 54 years old at the 2025 inventory.
It carries about 5,800 vehicles a day (traffic count year 2013).
Its listed owner is the state highway agency.
It is one of 100 of the 213 inventoried bridges in Colusa County rated fair (46.9%); 12 (5.6%) 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	Continuous prestressed concrete multiple box beam
Length	about 284 ft
Location	03-col-020-r22.09
NBI structure number	15 0078
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
Interstate 5 over Hillgate Road	1957	35,000	Good
Interstate 5 over Brush Creek	1967	35,000	Good
Interstate 5 over Cortina Creek Overflow	1946	33,000	Good
Interstate 5 over Farm Land Drain	1968	30,000	Fair
Interstate 5 over South Branch Sand Creek	1967	29,500	Good
Interstate 5 over Petroleum Creek	1967	18,000	Fair