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S5-n Mt Shasta Off over Interstate 5

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

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

S5-n Mt Shasta Off over Interstate 5 in Siskiyou County, California, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the deck, rated 5 (fair condition) on the 0-9 scale.
It was built in 1964, making it 61 years old at the 2025 inventory.
It carries about 1,700 vehicles a day (traffic count year 2015).
Its listed owner is the state highway agency.
It is one of 230 of the 425 inventoried bridges in Siskiyou County rated fair (54.1%); 25 (5.9%) 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 concrete multiple box beam
Length	about 417 ft
Location	02-sis-005-r12.06
NBI structure number	02 0091K
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 SB over UP RR & Amtrak	1964	20,000	Fair
Interstate 5 NB over UP RR & Amtrak	1964	20,000	Fair
Interstate 5 over Mott Road	1976	20,000	Good
Interstate 5 over Mott Road	1976	20,000	Fair
Interstate 5 over Dunsmuir Ave	1976	19,200	Good
Interstate 5 over Sacramento UP RR Amtrak	1955	18,000	Good