The M6 Stage 1 contractors have reached an agreement with the NSW Government to resume work two years after a sink hole interrupted tunnelling.
The CGU consortium, made up of CPB Contractors, Ghella, and UGL, was awarded the design and construct contract and construction commenced in February 2022. Around 90% of the tunnelling and almost half of the tunnel fit-out had already been completed when disaster struck.
In March 2024 we reported that a 20-metre-wide sink hole appeared above the construction works of the M6 motorway tunnel, causing a two-storey building to sag. Concrete was poured into the sink hole to prevent the building’s collapse.
The NSW Government revealed three days ago that two subsidence events occurred in March 2024 and all tunnelling ceased, with all significant underground works stopping by early 2025.
For more than two years, the state government and Transport for NSW (TfNSW) have been arguing with the CGU consortium that was claiming for costs related to the two subsidence events in 2024.
However, the NSW Labor Government stated an agreement has now been reached and CGU will immediately resume all activities required to complete the project under the original design and construct contract. Only 250 metres of excavation of the main tunnel remains.
“The agreement also means Transport and CGU have reached a consensus that there are viable technical solutions to complete the remainder of the project,” the state government said in a statement.
“Under the agreement, CGU has also agreed not to pursue contractual claims against Transport or the NSW Government for costs related to the two subsidence events in 2024 and will work to rectify this area.”
The consortium contractors have agreed to optimise delivery as they remobilise to the site over the coming weeks and TfNSW will provide an update on the expected completion timeline in due course.
Image: Sydney’s unfinished M6 Motorway Stage 1. Credit: TfNSW
About the author
Desi Corbett
Desi is the Editor of Concrete in Australia, at the helm since December 2013, and our weekly news writer since 2016. Her expertise in this field forms part of a journalism career spanning three decades. To get in touch please email desi@corbettcomms.com