Crewe-based piling company Terrawise Construction was given just two weekends to install foundations for new overhead rail lines. NCE reports on how the team pulled it off.
As part of its Anglia Structure Renewals programme for Network Rail, Morgan Sindall was awarded the contract to install the new overhead line equipment at Harold Wood in east London, including the foundations package. Rather than opting for traditional reinforced concrete foundations, steel tube was chosen as the preferred option.
The main reason for choosing the driven tube foundation was programme - only two, 29 hour possessions had been allocated for foundation construction.
Having established a successful relationship on previous contracts, Morgan Sindall approached Terrawise Construction to tender the work and subsequently awarded it to the Crewe-based company.
Piling in a rail environment has one major drawback - restricted access to the worksite, preventing the use of traditional piling rigs. Concentrating on overcoming this hindrance,
Terrawise carried out extensive research in the development of piling equipment, focusing on piling hammers that can easily attach and interchange with commonly used road rail vehicles (RRVs).
Terrawise made use of its fleet of Movax side-grip hammers and BSP hydraulic hammers, both of which are ideal for the rail environment and have been key to delivery of the contract at Harold Wood.
The foundation design for each leg of the portal gantry was a single 610mm diameter, steel tubular pile, varying in length from 6m to 8.5m. The leg of the gantry is fixed directly to the pile via a steel transfer plate.
No curing time
“This design is not only quick to install but there is no concrete, and therefore no curing time. This allows the structure to be landed immediately after pile installation and has a significant time saving on the contract programme,” says Terrawise contract manager Dave Swann.
The work was completed in December 2011. “Stage 1 was carried out using the Movax. It can grip the tube in the horizontal position then manipulate itself, pitching the pile in the vertical position.
Typically the Movax will drive the pile 3m to 5m. At this point the Movax attachment is swapped for the BSP hammer and stage 2 is to back drive the pile to depth.” Swann explains.
On each of the two weekends 20 piles were installed using two Monster Bug RRVs, one with the Movax attachment and one with the BSP Hammer. It was supplemented with an additional RRV and trailer delivering the piles.
Morgan Sindall project manager Simon Westerly says: “Installing the 40 piles for the new structures exceeded my expectations and has helped put our programme back on track.”