TBM sets new southern hemisphere record

2 July 2020

Auckland, New Zealand has witnessed a new pipejacking record for the longest single drive in the southern hemisphere by a TBM with a diameter greater than 3m.

Contractor McConnell Dowell used a closed-face Herrenknecht TBM to bore a total length of 1,216m, finally breaking through at Khyber Pass Road in the city centre on 29 June 2020.

Boring at up to 30m below ground level, the machine tunnelled through more than a kilometre of basalt rock, negotiating curves of 750m radius and exerting considerable pressure on the interjacking stations.

The pipejack forms part of Auckland’s NZ$400m Hunua 4 watermain project, a 31km pipeline on which construction started in 2012 and is due to finish in early 2021.

Construction over the 31km has been mostly open trenching although this phase has required tunnelling to minimise disruption to the city centre. A section of the pipeline is already in service as the works have been undertaken in 11 phases.

A final tunnelling drive remains, connecting Redoubt Road and the Khyber Pass reservoirs. At 1,296m long, it will set a new record.