The New M5 section of Sydney’s WestConnex has opened to traffic after almost 4 years of construction.

Also known as the M8 Motorway, it provides 9 kms of twin road tunnels between Kingsgrove and St Peters making it the longest road tunnel in Australia.

18,000 workers spent 21 million hours to deliver the project with tunnelling continuing 24/7 at a total cost of $4.3 billion.

The project included construction of a four-level interchange at St Peters built on a remediated landfill site. The interchange works included 10 bridges, two of which span the Alexandra Canal, and the longest being 288 metres.

579 precast box girder segments were made at Hunter and Coffs Harbour precast yards and used to construct 9 segmental bridges, erected using the balanced cantilever method.

62 precast girders were used for the St Peters cut and cover entry portals lifted into place by a 350t crawler crane.

The tunnel includes 33,000 architectural wall panels (some of which include LED lights to keep drivers alert), 177 jet fans and 1,600 kms of cable. 650,000 trees and shrubs are to be planted at the St Peters Interchange.

The project was delivered by CPB Dragados Samsung Joint Venture with primary designers Aurecon-Jacobs Joint Venture.

The M8 doubles the capacity of the M5 East Tunnels, and is expected to save motorists approx. 30 minutes. WestConnex is being delivered in four major stages: the New M4, New M5, M4-M5 Link and Rozelle Interchange, opening in 2023.

When complete, WestConnex will provide drivers with 33kms without traffic lights and connect with Sydney Gateway, taking drivers directly to the airport terminals.