London Cable Replacement Tunnels Category 3 Check

National Grid

Category 3 Check – Engineering Consulting Service:

National Grid is currently undertaking a major cable replacement program in the area of London. Part of that investment is the installation of high-voltage underground cables in a cable tunnel to be built between Hackney and Willesden.

Gall Zeidler Consultants (GZ) has been contracted to carry out a Category 3 Check of the design for the excavation and primary lining of the tunnel adit at Willesden Shaft.

The adit has a diameter of approximately 16 feet (4.8 meters) and is located approximately 80 feet (24 meters) below ground level in London Clay. The groundwater table is located approximately 6.6 feet (2 meters) below ground surface. The adit will be constructed using Sprayed Concrete Lining / Sequential Excavation Method (SCL / SEM).

The Category 3 Check includes the check of the structural integrity of the sprayed concrete lining elements during all temporary and the final construction stage in accordance with the project specifications and Eurocode.

LOCATION:
London, United Kingdom
DATE:
2011 – 2012
STRUCTURE:
Temporary Tunnel Adit
LENGTH:
130 feet (40 meters)
CROSS-SECTION:
Diameter of 15.7 feet (4.8 meters)
GEOLOGY:
London Clay, Groundwater About 72 feet (22 meters Above Tunnel)
COST:
$16 Million (adit)
CLIENT:
Costain Ltd.
OWNER:
National Grid