Sydney’s troubled M6 motorway project is moving again. The NSW government has reached an agreement with the private consortium building the $3.1bn twin-tunnel link, ending a two-year standoff that began when sinkholes opened beneath a Rockdale industrial estate in March 2024.
The Guardian Australia reported Friday that the consortium, a joint venture of CPB Contractors, Ghella and UGL known as CGU, will absorb the cost of finishing the remaining 250 metres of tunnel. The NSW government says the deal involves no extra cost to taxpayers, and that CGU has agreed to drop any contractual claims against the state related to the sinkhole damage.
NSW Motorways chief executive Camilla Drover said CGU would resume work immediately under existing contract terms. “We will provide an updated timeline for expected completion once we have it,” she said. Roads Minister Jenny Aitchison said the resolution protected the public purse. “Our priority has always been to complete this project under the existing contract,” she said.
Engineers are expected to use a technique called jet grouting to get through the compromised ground, injecting high-speed fluid to break up the soil before filling the cavity with grout.
Grahame Campbell, an engineer who project-managed the M4 and has researched infrastructure cost blowouts, said jet grouting was the only viable option given the geological conditions, but argued the saga was avoidable. “They should have done more investigation into the geology under the road system,” he told the Guardian Australia. “Disputes are common because the government doesn’t do the preliminary work necessary to fully define the terms of the contracts.”
The M6 was first approved in 2019 with a target completion date of 2024, later pushed to 2025. Tunnelling was 90 per cent complete when the sinkholes brought works to a halt. Motorists in Sydney’s south will now need to wait until at least 2028 for the Kogarah-to-Arncliffe link to open.
For tradies and businesses along the corridor, the restart is welcome news, but continued delays mean traffic pressure on surface roads in Sydney’s south will persist for the foreseeable future.
Frequently asked questions
What caused the M6 motorway to stop construction?
Sinkholes opened beneath a Rockdale industrial estate in March 2024 while tunnelling was under way, halting works with roughly 250 metres of tunnel still to complete.
Who is paying to fix the M6 tunnel problem?
Under the new agreement, the building consortium CGU, made up of CPB Contractors, Ghella and UGL, will absorb the cost of completing the remaining tunnel section. The NSW government says there will be no extra cost to taxpayers.
When will the M6 motorway open?
Completion is now expected no earlier than 2028. The project was originally due to finish in 2024, later revised to 2025, before the sinkhole stoppage.
What is jet grouting and why is it being used?
Jet grouting involves injecting high-speed fluid into unstable ground to break up the soil, then filling the resulting cavity with grout. Engineers say it is the most viable technique for tunnelling through the compromised ground beneath Rockdale.
Sourced from The Guardian Australia, Sydney Morning Herald. Original article.
