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U.S. Highway 101 over UP RR Spur

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

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

U.S. Highway 101 over UP RR Spur in San Mateo 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 1948 and reconstructed in 1969, making it 77 years old at the 2025 inventory.
It carries about 188,000 vehicles a day (traffic count year 2009).
Its listed owner is the state highway agency.
It is one of 100 of the 361 inventoried bridges in San Mateo County rated good (27.7%); 37 (10.2%) 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 149 ft
Location	04-sm-101-21.80-ssf
NBI structure number	35 0121
Condition class	Good

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

Bridge	Built	Vehicles/day	Condition
U.S. Highway 101 over San Mateo Creek	1928	236,000	Good
US 101 Rollins Rd over Transmission Canal	1928	232,000	Fair
US 101 Mcdonnell over Millbrae Slough	1947	226,000	Fair
US 101 W&e Bayshr over San Francisquito Creek	2018	225,800	Good
Holly Street over US Highway 101	1954	201,000	Fair
Whipple Avenue over US Highway 101	1958	201,000	Good