Hampshire: M3 J2-4a Smart Motorway Project

DAWSON-WAM was contracted by Balfour Beatty Major Project to construct new sheet piled retaining walls and bored concrete gantry piles to upgrade a critical section of the M3 Motorway to Smart Motorway.

The project will increase the capacity of the M3 between Junctions 2 and 4a by making the existing hard shoulder suitable for use as a running lane, improving some junctions to remove queuing traffic from the slip roads and main line carriageway and by introducing Managed Motorway technology.

The works involved the installation of approx. 1.5km of AZ king sheet pile (KSP) walls at over 30nr locations for ERAs or Gantry locations. Sheet piles were driven to level using the companies powerful ABI TM22 piling rig and 30VV hammer which is currently the most powerful setup available in the UK.

The versatility of the ABI TM22 was proven with the installation of 11nr Gantry foundations. Concrete bored piles locations of 900mm diameter were installed in groups of one or two ( one nr or two nr 900mm piles per gantry location) which were completed whilst a sheet piled wall location was being completed ie one visit for both types of piles. Piles were up to 14m long and installed by CFA technique with the rig using it’s quick docking facility to switch from sheet pile mode to auger mode and vice versa. Typically for a single pile location , the sheet piles would be installed in 2 days, one day for the concrete pile with the rig being moved to the next location at night.

Ancillary works included a concrete strip at the front of the sheet piles, weep holes, a King post wall ERA, Capping beams and fencing works.

Works were complete largely during 2016 between Nov 15 and August 16. Our Client was Balfour Beatty Major Projects. Contract value £1.5 million.

BBMP supplied the piles, stored at M1 J12 with the piles being delivered at night.