Waikato Expressway contractors are making an early start on the piles for the bridge which will span State Highway 1 at Cherry Lane.
The thud of pile driving is now set to begin later this month as preparations for the East-West bridge get underway two months earlier than planned.
A big, blue, 100 tonne crawler crane will be assembled on the site alongside SH1 in northern Tamahere when piling is about to begin.
A total of 21 pile casings will be driven up to 40m deep, said NZTA contractors City Edge Alliance in a statement.
One row of pile casings will be driven to support each end of the bridge, and two rows will support the central columns supporting the middle of the bridge.
Metal pile casings will be driven into the ground using a ‘bottom driven’ technique. The casings will be driven by a 10-tonne weight (or hammer) suspended from the crane. The hammer will be lifted and dropped repeatedly inside the pile casing. The hammer falls on the foot of the pile casing to drive it into the ground. This ‘bottom driven’ technique causes less noise than ‘top driven’ piling.
Once each pile casing reaches its required depth, a steel reinforcing cage will be dropped inside and the casing filled with concrete. This forms each finished bridge pile.
Residents living near the East-West Bridge site will experience some vibration and additional noise, City Edge Alliance said.
Piling is expected to take up to eight weeks. Once complete, concrete crossheads will be formed on top of each row of piles to tie them together and support the bridge beams. Beams will be manufactured off-site and lifted into place by a crane.
Normal hours of work for the piling team are 7:30am to 6:00pm, Monday to Saturday.
The Southern Interchange is part of the Hamilton Section of the Waikato Expressway. It will connect residents in Cherry Lane, Cambridge Road and Bollard Road with the city and with other parts of Tamahere.