JDK was commissioned to work on the NorthConnex project, providing technical assistance for highway services, interchange structures, and associated transportation infrastructure to Sydney commuters and communities.

The NorthConnex project provides a multi-lane motorway that links the M1 Pacific Motorway at Wahroonga NSW to the M2 Motorway at West Pennant Hills, NSW. This project features twin motorway tunnels around 9 km in length and a height clearance of 5.30 m. The tunnels were constructed with a three-lane capacity in each direction, including two current lanes and a breakdown pull-off lane.

A northern interchange was included at the M1 Pacific Motorway and Pennant Hills Road, including sections of the tunnel for on-ramps and off-ramps to facilitate access to and from the Pacific Highway. A southern interchange with the Hills M2 Motorway and Pennant Hills Road was added, including sections of the tunnel for on-ramps and off-ramps. Integration works included carriageway extensions and modifications. Infrastructure works included widening and lengthening bridges and viaducts and modifying local roads.




LendLease Bouygues
Joint Venture (LLBJV)


Sydney, Australia

Time Frame

April 2017 – September 2020


$3.72 billion


JDK carried out full-time coverage on this project with a streamlined approach, from the initial systematic capture of geotechnical and geological information to the final installation of support for remediation.

The project scope was broken down into the following three stages:

Step 1

  • Third-party geotechnical review and implementation of design
  • Geotechnical assessment of roof conditions
  • Rockfall remediation and prevention
  • Crack mapping, and geotechnical assessments about repair and remediation of finial lining.
  • Water seepage mapping, remediation, and recommendations
  • Geological defect mapping, monitoring, and remediation
  • Geotechnical assessment and confirmation of ground conditions for support type design compliance
  • Permit to excavate and permit to tunnel (review and implementation) through poor ground conditions.

Step 2

  • Permit to trench through poor ground conditions with a high defect frequency and weak rock mass.
  • Review of electrical and water conduit installations across 40km+ of trenches within shale and sandstone
  • Third-party review of pad installs and pile design for surface signs installed through pilling operations and bearing capacity analysis.

Step 3

  • Management of 10 staff on site for final lining installation
  • Final lining installation, review, and remediation
  • Identification and review of final lining for installation of strip drains, and crack remediation by the designer’s specifications

Value Added to the Project

JDK completed the NorthConnex project, adding value across key areas and meeting all stakeholders’ needs. We interacted with teams across several disciplines and provided extensive geotechnical expertise to help manage and control tunnelling risk.

The implementation of monitoring controls was completed without any community complaints, client issues, or existing infrastructure damage. The project incorporated innovative data collection methods, which led to enhanced data quality and improved outcomes throughout the delivery process. The precise inferences of ground conditions enabled the client to allocate resources and maintain their deliverables schedule efficiently.

JDK completed all work safely, within budget, and on time while meeting the design and specifications of the contract. JDK is proud to have played a key role in developing critical infrastructure for the Sydney community.

NorthConnex Tunnel Construction Animation (Video by Transurban)

Project Highlights