Oakland, California, November 29, 2011 – the tunnel “breakthrough” occurred on November 29, 2011 at 2:37pm, when the tunnel’s eastern and western excavation sides were joined.

“The project team is very happy about the timely completion of the important milestone of the top heading breakthrough. The Caldecott project has substantiated again that technical expertise on the contractor’s as well as the owner’s side is the key element and a must for safe and successful tunneling,” Axel Nitschke, Ph.D., P.E. team leader for GZ on this project.

When the fourth bore opens to traffic in late 2013, it will eliminate the need to reverse the traffic direction in the existing center bore twice a day to accommodate peak traffic flows, with dedicated westbound and eastbound traffic lanes.

The Caldecott Fourth Bore Project is a partnership between the Federal Highway Administration, Caltrans, the Metropolitan Transportation Commission (MTC), the Contra Costa Transportation Authority (CCTA), and the Alameda County Transportation Commission (ACTC).

GZ is responsible for the technical construction management of the NATM section and supports the team with technical expertise and inspection services.