Sydney, New South Wales, Australia

Managing noise and vibration during the construction, nearby to residential areas, of the deepest traffic tunnels in Australia

Opened in 2020, NorthConnex is a nine-kilometer twin tunnel linking the M1 Pacific Motorway to the Hills M2 Motorway in north Sydney. The project also includes the integration of the new tunnel into the existing M2, requiring widening and an extra westbound lane for approximately 2km.

Considered the missing link to improving freight access, connectivity and reliability in the National Transport Network across Greater Sydney, NorthConnex has been designed to the highest safety standards as a solution to bypass one of New South Wales’ most congested routes, Pennant Hills Road.

We were first engaged at the tender phase by the contractor delivering the $3 billion project. As with all major infrastructure projects in metropolitan areas, there were significant noise and vibration aspects to be managed, particularly as there were residential neighbourhoods nearby.

We assessed operational traffic noise, developing and validating a noise model followed by the design of amended noise barrier heights and locations to ensure a feasible and reasonable approach was followed. Each façade of residences was identified. Where noise barriers would not meet criteria, upgraded glazing and mechanical ventilation to residences was required.

In accordance with the project approval conditions and community consultation, we prepared an Operational Noise report and Operational Noise management plan. The construction team was supported when local factors meant that slight variations in the design of the barriers was required. Our rapid response prevented any construction delays.

To allow 24-hour tunnelling to proceed, we designed both the acoustic sheds used during the project and the construction ventilation systems. We prepared Construction Noise and Vibration Impact Statements and Construction Noise and Vibration Management Plans in accordance with the project approval conditions. This included tunnelling using roadheaders beneath residential properties at night time.

During the construction phase, we monitored construction noise and vibration. Our efforts were crucial to the successful and timely opening of the much-anticipated NorthConnex bypass, the twin tunnels of which have the distinction of being the deepest in Australia.