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BAM Ritchies

Case Study: M4 Widening Newport to Cardiff

Client: Welsh Assembly Government

Designer: Jacobs

Main Contractor: Carillion Infrastructure

Location: South Wales

Date: 2007 - 2009

BAM Ritchies undertook a major slope stabilisation package for Carillion Infrastructure’s ECI contract for the Welsh Assembly Government to widen the M4 between Newport and Cardiff in South Wales.

Stabilisation commenced on the eastbound carriageway near to Junction 32 in the middle of 2007 and continued in a number of visits to site with completion on the westbound side near Junction 29 in October 2009.

In total some 4km of slope was stabilised.

The work completed included:

  • 9,850 soil nails/rock bolts using 20mm diameter galvanised GEWI bar inserted in 100mm diameter holes – total installed length – 29,983 metres
  • 21,414m2 hexagonal twist wire meshing
  • 22,450m2 of erosion control matting
  • 26,231m2 of hydro-seeding
  • 856 drains drilled in up to six metres deep with slotted plastic tubing installed in 60mm diameter holes.

The ground conditions varied from hard sandstones to glacial till.

Rigs used were two Boart Deltabase 100s and an excavator mounted drilling mast: all using augers and top hammers as required.

All work was carried out within traffic management to maintain traffic movement in both directions throughout the works.