State Route 123 (SR 123) is a state highway in the U.S. state of California in the San Francisco Bay Area. Named San Pablo Avenue for almost its entire length except for its northernmost , SR 123 is a major north–south state highway along the flats of the urban East Bay. Route 123 runs between Interstate 580 in Oakland in the south and Interstate 80 at Cutting Boulevard in Richmond in the north. San Pablo Avenue itself, a portion of Historic US 40, continues well past the SR 123 designation south to Downtown Oakland and north to Crockett. Route description SR 123 is a four-lane boulevard with a median strip for its entire length. Its southern terminus is at the underpass of Interstate 580 in Oakland. Going north, it passes through the cities of Emeryville, Berkeley, Albany, and El Cerrito. It briefly turns on Cutting Boulevard before entering Richmond at its northern terminus under Interstate 80. SR 123/San Pablo Avenue does not directly intersect with I-580 in Oakland, so drivers are instructed to get onto I-580 east via 35th Street, or I-80 east/I-580 west via West MacArthur Boulevard. The I-580 west on-ramp use to end just before the I-80 split at the MacArthur Maze, but was rebuilt to force traffic onto I-80 east and to prevent the merging and weaving of those trying to get onto I-80 west. Signage on I-580 does not mention SR 123; access is via I-580 west exit 19A/San Pablo Avenue/MacArthur Boulevard or I-580 east exit 19B/West Street. Signage on I-80 does not mention SR 123 either on SR 123's official northern terminus at exit 15/Cutting Boulevard or at the San Pablo Avenue intersection further north at I-80 exit 16B. San Pablo Avenue is sometimes used as an alternate route to the Eastshore Freeway (I-80/I-580) when that freeway becomes very congested. Major intersections along this route include 40th Street, Ashby Avenue (SR 13), University Avenue (which leads to UC Berkeley), Gilman Street, Marin Avenue, Central Avenue and Cutting Boulevard. Continuing on San Pablo Avenue past SR 123's southern terminus eventually leads to Downtown Oakland and Oakland City Hall where San Pablo Avenue ends. Continuing north on San Pablo Avenue after SR 123 turns west onto Cutting Boulevard in Richmond leads to the cities of San Pablo, Pinole, Hercules, Rodeo, and Crockett. In Hercules, San Pablo Avenue meets the terminus of SR 4 near I-80, and, after