U.S. HIGHWAY 101
U.S. HIGHWAY 101 in 04-Sm-101-21.61-Ssf, San Mateo County, California received a condition grade of C (49/100). Built in 1947, the bridge carries 188K vehicles daily on U.S. HIGHWAY 101 over Colma Creek.
U.S. HIGHWAY 101 carries a C on the BridgeSafety Condition Score with 49/100. Component ratings sit in the middle of the FHWA NBI distribution; rehabilitation programming is likely on the owning agency’s medium-term horizon.
The bridge was built in 1947 and is now 79 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 188,000 vehicles, with 9 lane(s) crossing Colma Creek. 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 79-year-old bridge located 04-Sm-101-21.61-Ssf in San Mateo County, California. The bridge carries U.S. HIGHWAY 101 over Colma Creek with 9 traffic lanes, handling approximately 188K vehicles per day. Built in 1947 and reconstructed in 1973, the structure spans 36.6 meters.
The bridge received a Condition Grade of C (49/100) based on Federal Highway Administration inspection data. Its deck is rated 5/9 (fair), superstructure 5/9 (fair), 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 49/100 (Grade C). Its deck is rated 5/9, superstructure 5/9, and substructure 7/9 on the NBI scale. The bridge is not classified as structurally deficient.
U.S. HIGHWAY 101 was built in 1947 and reconstructed in 1973, making it 79 years old. The average bridge age in the United States is 48 years.
U.S. HIGHWAY 101 carries approximately 188K vehicles per day (average daily traffic). The bridge has 9 traffic lanes. It is 36.6 meters long and located on U.S. HIGHWAY 101 in 04-Sm-101-21.61-Ssf, San Mateo 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-Sm-101-21.61-Ssf in San Mateo County, California. The bridge carries U.S. HIGHWAY 101 over Colma Creek. Its coordinates are 37.648694, -122.406336. It is maintained by State Highway Agency.
U.S. HIGHWAY 101 carries U.S. HIGHWAY 101 over Colma Creek. The bridge is 36.6 meters long and was built in 1947, with reconstruction in 1973.
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.