Mega tunnel ‘possible but unpredictable’
New Zealand’s construction industry is not well equipped to build the mega tunnel floated by the government, an expert says.
Last week Transport Minister Simeon Brown announced the Government had asked NZTA Waka Kotahi to re-investigate plans for a 4km road tunnel linking the Terrace Tunnel with Wellington Rd in Kilbirnie. The idea was dismissed by the now-disbanded Let’s Get Wellington Moving because of the cost.
Professor Suzanne Wilkinson, who specialises in construction management at Massey University, said the 4km tunnel project would be feasible, but the question of cost would be unpredictable because groundwork was “very uncertain”.
“Tunnels are complex infrastructure. Any building below ground adds significant risks – collapse, water ingress, difficult ground conditions, failing equipment which is hard to remove.”
Wilkinson was part of a nationally funded project called CanConstructNZ, which assessed the local market’s ability to deliver infrastructure projects.
She said it was unlikely that there were sufficient specialist engineers, project managers and skilled workers to undertake such a significant tunnelling project “unless we start training now or recruiting from overseas”.
“Our ability to plan for these projects in terms of capacity and capability is low.”
Assuming tunnel boring machinery would be used to make the tunnel, the required equipment was not in the country. Alice, the tunnel borer used for Waterview, was dismantled and sent back overseas in 2016.
Because New Zealand did not have a lot of tunnelling expertise, the tunnel would most likely end up being delivered, as the Waterview Tunnel was, through an international alliance.
“As normal with complex infrastructure projects, we would expect considerable deviation from the initial time and cost aspects.”
Overseas there have also been prominent issues with large tunnelling machines getting stuck – back in 2014, the tunnelling machine Bertha was damaged and stuck underground in Seattle for almost four years after hitting a steel pipe. Wilkinson said tunnel boring machines getting stuck was a common event.
Rongotai MP Julie Anne Genter, a former transport planner, had run some numbers. She said that for the approximate cost of the tunnel – $9 billion if it cost about the same per metre as the Mt Victoria tunnel’s cost estimate – the Government could put in surface light rail in Auckland and Wellington, while still having billions left over for the new InterIslander ferries.
“I just don’t understand how someone could think surface light rail was unaffordable or unachievable in Wellington, and then go, ‘Look at this four kilometre car tunnel underground’.”
There was an “unbelievable amount of denial” about what worked for transport within cities, Genter said.
“The places where we need roads to move our high volume primary products to market are not between Wellington airport and the CBD. People going to the airport can’t take their cars with them on the plane – that’s the perfect situation for public transport.”