Three-year delay to new Sydney motorway risks getting much longer

A new multibillion-dollar underground motorway in Sydney’s south is at risk of opening later than the already delayed completion date of 2028, with the NSW roads minister saying the new date will be determined by a complex technical fix being negotiated by the government and contractors.

The opening of the M6 motorway had been delayed by three years to the end of 2028 due to two sinkholes opening up early last year above one of the tunnels being dug for the project. In May, contractors revealed that they would stop all work indefinitely because of the tunnelling conditions, before later agreeing to complete surface works.

Under repeated questioning from the opposition, Roads Minister Jenny Aitchison declined to give a time frame for completion of the project because of the “very serious” geotechnical problems that had to be resolved.

“Until we fund a technical solution, we cannot give a timeline. We want to make sure that we get the right solution [and] that there’s not an additional cost to the taxpayers on this,” she told a budget estimates hearing on Tuesday.

“I’m not going to give you an arbitrary time frame … because there is too much work that is being undertaken by the department and by the contractor to try and resolve the issue.”

Grilled about whether Transport for NSW had provided her advice that the project could be delayed beyond 2030, she said there was “always a risk that it could be of any time frame” but she did not recall receiving such a date, saying “maybe I have, maybe I haven’t”.

A revised completion date of late 2028 for the $3.1 billion project was confirmed by the government late last year, almost six months before contractors said they would stop all work.

Asked whether the 2028 time frame was still possible, Aitchison said engineers had to be allowed to work on a solution instead of setting them arbitrary time frames. “I don’t have a view on whether it’s achievable on that particular project. I’m not an engineer,” she said.

Transport for NSW secretary Josh Murray said the agency had yet to provide an update to the government about the latest findings from technical assessments, but he expected that to happen within the coming weeks.

About six weeks after saying they would cease all work indefinitely, contractors reached a deal with the Transport Department in July to complete surface road works, new walking and cycling paths and parkland as part of the project by the end of the year.

Transport for NSW also reached an agreement with contractors last month for them to keep maintaining the security and safety of the tunnels and construction sites for three months while the technical and commercial assessments were under way.

The first stage of the M6 comprises four-kilometre twin tunnels between President Avenue at Kogarah and the WestConnex motorway at Arncliffe. The sinkholes stopped work on a 244-metre section of the tunnels at Rockdale.

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