Milestone day for Auckland: new tunnel boring machine launched. Video / City Rail Link
The risk of derailing Auckland's $4.4 City Rail Link project has led the Government to allow a small crew to continue working under level 4 lockdown.
City Rail Link Ltd chief executive Dr Sean Sweeney said there was a risk of the giant tunnel boring machine getting trapped deep belowthe city.
"The pressure from earth settling around any stationary tunnel boring machine could trap that machine. If that happened here, the costs involved in freeing the machine would completely derail the project."
City Rail Link Ltd chief executive Dr Sean Sweeney. Photo / Greg Bowker
In 2013, a huge tunnel boring machine got trapped on a rail project in the American city of Seattle. It took two years for a recovery pit to be dug to lift and repair the machine's head cutter before work could resume.
Sweeney said Auckland's $13 million tunnel boring machine, named Dame Whina Cooper, would be operating at a reduced level. Instead of running 24 hours, five days a week, it is expected to operate from 7am to 7pm on weekdays.
"The Government's 'okay' is a very welcome one, giving us the assurance that a potential lockdown risk underground has been removed.
"Our priority will be to keep the machine's crew safe. They will be working under strict health and safety guidelines that include wearing protective clothing and keeping a proper distance from workmates."
Since May, the tunnel boring machine has progressed 367m from Mt Eden, heading towards the city. So far the giant cutter head has excavated 29,500 tonnes of spoil and 298 concrete rings have been installed. When this job is completed it will return to Mt Eden and dig a second, parallel tunnel.
Sweeney said the lockdown would have a significant impact on the project, but this will not be fully quantified until sometime after the lockdown ends.
This comes as an update on the CRL project for Auckland Council's audit and risk committee next week says construction is at a critical phase, with consequent uncertainty remaining about cost and schedule.
Inside the 130m long tunnel boring machine. Photo / City Rail Link Ltd
Sweeney said the Ministry of Business, Innovation and Employment (MBIE) had been advised of the rationale for operating the tunnel boring machine within current regulations.
It is being operated by the main contractor, the Link Alliance.
The City Rail Link is a 3.4km rail tunnel connecting Britomart in the city with the Mt Eden station. When complete in 2024, patronage will increase from 15,000 people per hour to 22,500.
To reach its full potential of 54,000 people per hour will cost a further $6.7b to upgrade the existing rail network in the future decades.
This will include additional tracks and trains, lengthening platforms for nine-car trains, removing all level crossing on the southern and western lines and a signalling upgrade.
