Caldecott Tunnel Improvement
Contra Costa Transportation Authority / Caltrans
Existing East Portal of the 3rd Bore and site preparation for the new 4th Bore
Caldecott Tunnel Improvement
Construction Management Services:
The existing Caldecott Tunnel consists of three two-lane tunnels that connect Alameda and Contra Costa counties via State Route 24 (SR–24). In order to reduce traffic congestion and delays, the project includes the construction of a fourth tunnel with seven cross passages to the existing third Bore, using Sequential Excavation Methods (SEM/NATM).
Excavation will primarily include the use of roadheaders and controlled blasting as needed. Tunnel ground support in the challenging geology will consist of fiber reinforced shotcrete, lattice girders, different types of rock bolts, face bolts, and different types of spiling as pre-support and pipe canopies in the portal areas. After completion of the excavation, a waterproofing membrane will be installed, followed by a cast–in–place reinforced concrete final lining.
The California Department of Transportation (Caltrans) leads the construction management (CM) team on site. Gall Zeidler Consultants is responsible for the technical construction management of the NATM section and supports the team with technical expertise and inspection services.
- LOCATION:
- Oakland, California
- DATE:
- 2009-Present
- STRUCTURE:
- Two-lane highway tunnel
- Length:
- 3,389 feet (1,033 meters)
- CROSS-SECTION:
- 49 feet (15 meters)
- GEOLOGY:
- Moraga Formation (volcanic rocks). Orinda formation (sandstone, siltstone, mudstone, and conglomerate). Claremont formation (chert, shale, and sandstone). Sobrante formation (sandstone and shale)
- Cost:
- Approximately $ 260 million
- CLIENT:
- Parsons Brinckerhoff Construction Management Services
- Owner:
- Contra Costa Transportation Authority / Caltrans