The first of 3400 stone columns, which would reach from Mount Maunganui to Waihi Beach if they were laid out end-to-end, have been installed on the Baypark to Bayfair Link project.

The columns will improve the ground conditions throughout the site so it can eventually take the weight of the two flyovers.

Installing stone columns involves putting vertical columns of stone (gravel) into the ground and using vibration to move the sand to make way for the stone. This is being done using an 80-tonne crawler crane with a 3.2 tonne ‘vibroflot' attached – the vibrating element that carries out the compaction and delivers the stone.

NZ Transport Agency project manager John McCarthy says the installation of the columns is a significant milestone for the project.

'The stone columns will cover more than two rugby fields and use enough gravel to fill eight Olympic-size swimming pools.

'They push against the surrounding ground, increasing its density and enabling the ground to support the weight of the on and off ramps that will be built on top. It will also protect the ground from the risks of liquefaction during an earthquake.”

Construction of the 3400 stone columns is expected to take approximately 10 months.

The Baypark to Bayfair Link is designed to reduce congestion and improve safety by separating local and state highway traffic and providing walking and cycling connections.

The key features include the construction of two flyovers and improvements to the SH29A and Truman Lane roundabout, and the SH2 Maunganui-Girven Roads roundabout.