WestConnex M4 Widening

Widening a 7.5-kilometre stretch of existing motorway (to four lanes each way) involved an upgrade of existing interchanges, construction of a new 1.8-kilometre viaduct, new bridges over Duck River and Deniehy Street, retaining walls, 4.9 kilometres of noise barriers, and a new stretch of shared path/cycleway.


Given traffic congestion and population growth along this stretch of Western Sydney, project goals were to minimise noise and visual impacts on the adjacent community, improve the visual experience of the motorway and activate forgotten spaces under existing viaducts, with improved wayfinding signage and street furniture.


Simple but strong architectural elements will integrate the new bridges, interchanges, retaining walls and noise barriers with existing motorway elements. A secondary layer of expression through colour and pattern will embed the new elements into local landscapes.


    Rizzani CPB Joint Venture


    Pitt Street (Parramatta) to Homebush Bay Drive

  • YEAR



    7.5 km



    Mary Anne McGirr Miriam Enoch



Colour, form and finishes for the new urban design elements will help them interact dynamically with existing structures to improve journey legibility and experience. At the Silverwater Road Interchange, a pair of patterned, cantilevered walls reference the local industrial context through their abstracted pattern of steel truss forms.


Viaduct and bridge piers both reference and contrast existing adjacent viaducts, with their clean lines and smooth circular piers. On the viaduct and at interchanges, noise walls reference the colour of a Cumberland Plain native flower — Sarsparilla Hardenbergia violacea, with more neutral colours applied to noise walls facing into residential areas.


Recognising the limited planting opportunities in narrow corridors, the landscape strategy will maximise impact at the interchanges with mature native plantings. Elsewhere, species will be considered as part of the overall site remediation.

03_WestConnex M4 Analysis 2_LCZ 2_sm

“We achieved some great urban outcomes on the WestConnex M4 Widening project — improving the journey experience, minimising visual impacts, activating forgotten spaces and improving legibility, wayfinding and safety for motorists, cyclists and pedestrians.”