Abigroup Contractors Pty Ltd
2010 - Continuing
  • Geotechnical Design & Advice
  • Detailed Geotechnical Investigations
  • Laboratory Testing


Hunter Expressway Project

In October 2010, Abigroup Contractors Pty Ltd were awarded the contract for design and construction of the western section of the Hunter Expressway. The design and construct contract involves the building of 27 km of four lane divided highway between Kurri Kurri and Branxton, 22 bridges and four grade separated interchanges. The work includes approximately three million cubic metres of earthworks, the treatment of two mine subsidence areas and provides employment for over 600 people.

Douglas Partners has been contracted by Abigroup to provide geotechnical advice for the design of earthworks along the project. DP Project Manager Fiona MacGregor said: “While many of the geotechnical issues are common to other major highway projects, there are some technically challenging and interesting features on this project which require detailed geotechnical investigation and analysis. These include construction of the highway over old underground coal mines and determining strategies for managing rocks which deteriorate rapidly upon exposure.”
During the tender period for the project selected rock cores were left outside and exposed to the weather. Some sections of these cores deteriorated rapidly within a few days from high strength rock to silt. This deterioration potentially has significant consequences on the stability and erosion of cuts and fills. Detailed investigations including X-ray diffraction and petrological analysis have been undertaken to determine the reasons for the rock breakdown, which was shown to be a combination of acid sulphate rocks and expansive clay minerals. Douglas Partners has provided advice on methods for managing these materials.
Construction of the western section of the Hunter Expressway commenced in early 2011 and is due for completion by the end of 2013. Once complete it will form part of the new Hunter Expressway linking the F3 Freeway at Seahampton to the New England Highway, west of Branxton.
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