• Capabilities: Engineering, Civil Engineering, Structural Engineering, Tunneling and Underground Infra, Water Management, Geotechnical Engineering, Transportation Planning, Master Planning and Sustainable Urban Development
  • Sectors: Transportation, Water and Utilities, Highways and Intelligent Transport Systems

Westconnex New M4

Sydney, New South Wales, Australia - Designing an integrated, urban motorway to boost mobility and connectivity for a rapidly growing Western Sydney.


of new M4 motorway

1.6 million

population increase in Sydney by 2036 can be accommodated with this design
Westconnex New M4 Detailed Design

WestConnex, a 33 kilometre motorway being built in three stages linking Sydney’s west to the City, Airport, Port and existing major roads, is a key component of a massive investment by the New South Wales Government in new urban infrastructure. 

A core part of WestConnex is the 6.5 kilometre new M4 featuring 5.5 kilometres of twin motorway mined tunnels. As part of a joint venture, Arcadis provided all civil, structural and building design services, including major cut and cover structures, numerous bridges, complex roadworks and sensitive flooding and drainage systems.

Such complex and high profile urban infrastructure came with significant design, environmental and technical challenges. These included minimal property acquisition to ease planning approval and reduce community impacts, accelerated construction deadlines, and the need to align with the planning priorities of all stakeholders.

Innovation and meticulous planning were crucial. One of the most impressive was the challenge of a new interchange to be built in the middle of one of Sydney’s busiest road networks while maintaining all existing car and pedestrian connections that saw over 50 proposals reviewed and assessed before the final compact loop design was approved.

The project also required the installation of two ventilation structures for WestConnex on limited land. Arcadis completed complex three-dimensional geotechnical modelling to develop a robust design particularly for one of the structures that was required to accommodate an unconventional ventilation structure, technical constraints and pressing con-struction timelines.

WestConnex is part of an integrated transport plan to keep Sydney moving as it accommodates another 1.6 million people over the next 20 years, with much of the expected population growth in Western Sydney. Faster, safer transport linkages will not only underpin economic and business growth across the city, but WestConnex will also deliver 18 hectares of new open space and over 14 kilometres of cycle and pedestrian paths.

Westconnex New M4 Detailed Design aerial view
HBD looking east



of new M4 motorway

1.6 million

population increase in Sydney by 2036 can be accommodated with this design

Questions about this project

Syd Gamble

Senior Technical Director +612 8907 9106 Ask me a question
Share on Wechat
"Scan QR Code" on WeChat and click ··· to share.