Caldecott Tunnel

Caldecott Tunnel

The Caldecott Tunnel, western end, before the construction of the fourth bore
Overview
Location	Oakland / Contra Costa County, California
Coordinates	37°51′17″N 122°13′00″W / 37.8548°N 122.2166°W / 37.8548; -122.2166
Route	SR 24 (William Byron Rumford Freeway)
Operation
Opened	Bores 1 & 2: 1937 Bore 3: 1964 Bore 4: 2013
Operator	Caltrans
Technical
Length	Bores 1 & 2: 3,610 ft (1,100 m) Bore 3: 3,771 ft (1,149 m) Bore 4: 3,389 ft (1,033 m)
No. of lanes	2 per bore
Tunnel clearance	Bore 1: 14.58 feet (4.44 m) Bore 2: 14.5 feet (4.4 m) Bore 3: 15.5 feet (4.7 m) Bore 4: 15.5 feet (4.7 m)

The Caldecott Tunnel is an east-west highway tunnel through the Berkeley Hills between Oakland and Orinda, California. Its four bores carry California State Route 24. Named after Thomas E. Caldecott, former mayor of Berkeley, it opened in 1937 as a two-bore tunnel. The third bore opened in 1964 and the fourth bore in 2013. Currently, the two oldest bores carry eastbound traffic and the two newest bores carry westbound traffic.

The east-west tunnel is signed as a part of State Route 24 and connects Oakland to central Contra Costa County. It is named after Thomas E. Caldecott (1878–1951), 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 3,610 feet (1,100 m) in length. Both carry two lanes each of eastbound traffic. Bore 3, completed in 1964, is 3,771 feet (1,149 m) in length. Bore 4 (the northernmost bore), completed in 2013, is 3,389 feet (1,033 m) in length. Bores 3 and 4 carry two lanes each of westbound traffic.

The active Hayward Fault runs just west of the western portals of the tunnel.

In the 19th century, traffic over the Berkeley Hills in this area went up Harwood Canyon, now known as Claremont Canyon (behind the Claremont Hotel). The road leading up the canyon from the west was initially called Harwood's Road, later changed to Telegraph Road, and finally, Claremont. The road on the other side of the hills was, and remains, Fish Ranch Road. An inn and stage coach stop called the Summit House once existed at the summit.

The idea of a tunnel through the hills began as early as 1860. In that year, the idea was proposed and rejected by the citizens of Alameda and Contra Costa Counties. It was revived in 1871 with a proposal which described a route running from the end of Broadway, similar to the actual routing of today's Caldecott Tunnel although it is not clear from the description exactly which canyon was being referred to. The proposed tunnel would be only some 500 feet long and would have its outlet in the San Pablo Creek watershed with a road leading into Lafayette. A franchise was granted to a group of developers who passed the franchise onto another group. The proposal languished until the turn of the century.