U.S. HIGHWAY 101
U.S. HIGHWAY 101 in 04-Mrn-101-14.71-Srf, Marin County, California received a condition grade of B (66/100). Built in 1952, the bridge carries 151K vehicles daily on U.S. HIGHWAY 101 over Lucas Valley Road.
U.S. HIGHWAY 101 carries a B on the BridgeSafety Condition Score with 66/100. 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 1952 and is now 74 years old, at or past the typical 50-year design life for bridges of its vintage. Maintenance and inspection cycles are correspondingly more involved than for newer structures. U.S. HIGHWAY 101 carries an average daily traffic count of 151,000 vehicles, with 10 lane(s) crossing Lucas Valley 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
U.S. HIGHWAY 101 is a 74-year-old bridge located 04-Mrn-101-14.71-Srf in Marin County, California. The bridge carries U.S. HIGHWAY 101 over Lucas Valley Road with 10 traffic lanes, handling approximately 151K vehicles per day. Built in 1952 and reconstructed in 1987, the structure spans 31.4 meters.
The bridge received a Condition Grade of B (66/100) based on Federal Highway Administration inspection data. Its deck is rated 7/9 (good), superstructure 7/9 (good), and substructure 7/9 (good).
This bridge is owned and maintained by State Highway Agency.
Location Map
Frequently Asked Questions
U.S. HIGHWAY 101 has a Condition Score of 66/100 (Grade B). Its deck is rated 7/9, superstructure 7/9, and substructure 7/9 on the NBI scale. The bridge is not classified as structurally deficient.
U.S. HIGHWAY 101 was built in 1952 and reconstructed in 1987, making it 74 years old. The average bridge age in the United States is 48 years.
U.S. HIGHWAY 101 carries approximately 151K vehicles per day (average daily traffic). The bridge has 10 traffic lanes. It is 31.4 meters long and located on U.S. HIGHWAY 101 in 04-Mrn-101-14.71-Srf, Marin County, California.
No, U.S. 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.
U.S. HIGHWAY 101 is located 04-Mrn-101-14.71-Srf in Marin County, California. The bridge carries U.S. HIGHWAY 101 over Lucas Valley Road. Its coordinates are 38.020950, -122.538964. It is maintained by State Highway Agency.
U.S. HIGHWAY 101 carries U.S. HIGHWAY 101 over Lucas Valley Road. The bridge is 31.4 meters long and was built in 1952, 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.