Boring began yesterday on the Caldecott Tunnel’s fourth bore in California. The job is expected to take three years to complete. The tunnel is being bored by roadheader.
The fourth bore project relies on almost USD 198M in federal stimulus dollars, making it America’s second largest investment of Recovery Act highway funds.
When completed in 2013, the new 1.03km tunnel will have 3.65m lanes, shoulders and emergency walkways.
The Caldecott Tunnel currently has three bores, which gives drivers a total of six lanes. The USD 420M project will create a two-lane tunnel bore north of the existing three Caldecott tunnels.
The roadheader will tunnel west toward Oakland from Orinda to be met in the months ahead by two smaller roadheaders boring eastward. Work crews will advance from both sides of the new tunnel, excavating and stabilizing small segments as they go, moving one to two metres a day.
