Client name: Leighton Contractors Pty Ltd

Duration: October 2013 - ongoing

Location: MacKays to Linden, Wellington, New Zealand

Working collaboratively with the client in the field – providing confidence in the geotechnical model, and time and cost saving solutions.

Situation

The Transmission Gully Motorway Project consists of 27km of dual carriageway, 3 interchanges and 28 structures, crossing varying geology from soft compressible soils, potentially liquefiable soils, numerous fault lines and very steep terrain  creating over 6 million cubic metres of earthworks to be managed during the project.

Leighton required us to provide additional geotechnical data along the alignment to increase their confidence in the geotechnical model – by showing our clear understanding of the local geology, geotechnical conditions and associated risks, pertinent to the geotechnical design.

Solution

Our experienced staff were able to apply their high levels of knowledge to ensure accurate logging of the soil and rock mass – data that otherwise could potentially be interpreted incorrectly or become skewed.

The use of our newly purchased rotary drilling rig, across rough and steep terrain, meant an efficient recovery of data  reducing time spent in field, and therefore costs to the client.

Utilising software tablets on site to collect data significantly reduced the turnaround time in the provision of for the production of logs – cutting rework time in the office, and reducing labour costs for the project. 

Being fully digitised onsite, also allowed for effective and efficient data manipulation ensuring ready updating of laboratory scheduling and design when required.

Our in-house geotechnical, drilling and testing capabilities available provided one contact with a full understanding of the greater scope of the project – making for seamless interpretation of the data and design.

Result

Providing our client with a greater understanding around the difficult geology encountered at the location, has reassured their positive view and understanding of the geotechnical model. 

Our fast and efficient provision of detailed site investigation data has created cost savings in the design approach  supporting enhanced road safety with a reduced likelihood for landslides, floods or damage caused from storms or earthquakes.

The Transmission Gully  Motorway will be a key component of the 110km Wellington Northern Corridor Road of National Significance, which, when fully completed will provide a safer, more reliable and efficient connection from Levin to Wellington.