Piling completed for new gantries on A38 Saltash Tunnel upgrade

Foundation works to support new gantries for electronic signs on the A38 approaches to the Saltash Tunnel in Cornwall have been completed as part of National Highways’ £25M tunnel modernisation programme.

Specialist contractor Van Elle carried out the piling on behalf of Taylor Woodrow, the principal civil engineering contractor for the A38 Saltash Tunnel technology upgrade scheme.

The four-week operation, which was completed last week, involved the installation of foundations for gantries that will support new electronic signs providing live traffic and safety information.

A National Highways spokesperson told GE that continuous flight auger (CFA) piling was selected for the works due to its low noise levels, due to the sites being close to residential properties, and the good rate of delivery.

“The piling work involves digging up to a depth of five metres on the approaches to the tunnel for the installation of four, eight by nine-metre gantries,” they added.

Ground conditions across the work areas were generally comprised of weak mudstone.

“A complication we had was piling adjacent to local and national/international fibre optic cables. Both Virgin Media and Vodafone ducts lie beneath two of the four MS4 gantry bases, and these needed to be slewed and lowered so that they lie in between the two rows of piles. These were then protected during piling by building in 600 sleeves within the piling platform,” the spokesperson said.