Caldecott Tunnel

The Caldecott Tunnel is a three-bore highway tunnel through the Berkeley Hills between Oakland, California and Contra Costa County, California. The east-west tunnel is signed as a part of State Route 24, which is also known as the William Byron Rumford Freeway from Interstate 580 to Walnut Creek, and connects Oakland to bedroom communities in Contra Costa County. (The name of the freeway was the Grove-Shafter Freeway until 1980, when it was named after Rumford.) The tunnel is named after Thomas E. Caldecott (1878–1951), mayor of Berkeley from 1930–1932, member of the Alameda County Board of Supervisors 1933-1945, and president of Joint Highway District 13, which built the first two bores.

Bore 1 (the southernmost bore) and Bore 2 were completed in 1937 and are each 3,610 feet (1,100 m) long and carry two lanes of traffic. Bore 3 (the northernmost bore), built in 1964, is 3,771 feet (1,149 m) in length, and also carries two traffic lanes.

The middle bore (Bore 2) can be shifted to accommodate heavy traffic. Generally, it carries westbound traffic from about midnight to noon and eastbound traffic from about noon to midnight.

Construction of a fourth bore began in January 2010. Cost of construction is estimated at $400 million, of which the American Recovery and Reinvestment Act will provide $280 million.