US HIGHWAY 101
US HIGHWAY 101 in 04-Mrn-101-12.69-Srf, Marin County, California received a condition grade of B (74/100). Built in 1979, the bridge carries 180K vehicles daily on US HIGHWAY 101 over North San Pedro Road.
US HIGHWAY 101 carries a B on the BridgeSafety Condition Score with 74/100. Most component ratings are solid; one or two may show wear consistent with the structure’s age, but the bridge is not flagged as structurally deficient.
The bridge was built in 1979, making it 47 years old — past the early-life period but still well within typical service life. Routine inspections and modest repair work are normal for bridges in this age band. US HIGHWAY 101 carries an average daily traffic count of 180,000 vehicles, with 10 lane(s) crossing North San Pedro Road. The owning agency is State Highway Agency; bridge inspection records flow into the federal NBI database annually.
Component Ratings
The riding surface, evaluated for cracking, spalling, and wear
Beams, girders, and trusses that support the deck
Piers, abutments, and foundations below the deck
Bridge Details
About This Bridge
US HIGHWAY 101 is a 47-year-old bridge located 04-Mrn-101-12.69-Srf in Marin County, California. The bridge carries US HIGHWAY 101 over North San Pedro Road with 10 traffic lanes, handling approximately 180K vehicles per day. Built in 1979 and reconstructed in 1987, the structure spans 53.3 meters.
The bridge received a Condition Grade of B (74/100) based on Federal Highway Administration inspection data. Its deck is rated 6/9 (fair), superstructure 7/9 (good), and substructure 7/9 (good).
This bridge is owned and maintained by State Highway Agency.
Location Map
Frequently Asked Questions
US HIGHWAY 101 has a Condition Score of 74/100 (Grade B). Its deck is rated 6/9, superstructure 7/9, and substructure 7/9 on the NBI scale. The bridge is not classified as structurally deficient.
US HIGHWAY 101 was built in 1979 and reconstructed in 1987, making it 47 years old. The average bridge age in the United States is 48 years.
US HIGHWAY 101 carries approximately 180K vehicles per day (average daily traffic). The bridge has 10 traffic lanes. It is 53.3 meters long and located on US HIGHWAY 101 in 04-Mrn-101-12.69-Srf, Marin County, California.
No, US HIGHWAY 101 is not classified as structurally deficient. All three primary components (deck, superstructure, and substructure) are rated above 4 on the 0-9 NBI scale.
US HIGHWAY 101 is located 04-Mrn-101-12.69-Srf in Marin County, California. The bridge carries US HIGHWAY 101 over North San Pedro Road. Its coordinates are 37.994014, -122.531797. It is maintained by State Highway Agency.
US HIGHWAY 101 carries US HIGHWAY 101 over North San Pedro Road. The bridge is 53.3 meters long and was built in 1979, with reconstruction in 1987.
Condition Score is calculated from deck (33%), superstructure (33%), and substructure (34%) NBI ratings with an age penalty for bridges over 50 years.
Source: FHWA National Bridge Inventory, 2026.