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De Long Avenue over Ncrra (old Nwp RR)

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

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

De Long Avenue over Ncrra (old Nwp RR) in Marin 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 1974, making it 51 years old at the 2025 inventory.
It carries about 30,155 vehicles a day (traffic count year 2000).
Its listed owner is the state highway agency.
It is one of 91 of the 207 inventoried bridges in Marin County rated good (44.0%); 16 (7.7%) 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 prestressed concrete multiple box beam
Length	about 220 ft
Location	04-mrn-101-r21.15-nvto
NBI structure number	27 0103Y
Condition class	Good

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

Bridge	Built	Vehicles/day	Condition
US Highway 101 over North San Pedro Road	1979	180,000	Fair
U.S. Highway 101 over Lincoln Ave-n101 on Ramp	1938	180,000	Fair
U.S. Highway 101 over Linden Lane	1947	173,000	Good
U.S. Highway 101 over Ggt Bellam Andersen	1958	172,000	Good
U.S. Highway 101 over Corte Madera CR & Sfd Bl	1957	172,000	Fair
U.S. Highway 101 over Wornum Drive	1929	172,000	Good