Tunnel mining has begun at the site of the future Karangahape Station with a large excavator brought in to create a 15 metre long connection to the caverns of the future station.
Machinery is digging out the short tunnel from the temporary access shaft, 18 metres deep.
Dale Burtenshaw, deputy alliance director for Link Alliance said the connection would be critical.
“This connection is short, but it will become an important and busy ‘construction artery’ for us providing access for people, machines and material,” he said.
Once the 9.5 metre wide and 8m high arch-shaped tunnel is excavated a roadaheader will finish the connection before beginning to dig out the station platform tunnels.
“It’s a clear sign of work ramping up. Our focus is very much on welcoming the Tunnel Boring Machine at Karangahape Station at the end of next year on the first leg of its journey from Mt Eden,” said Burtenshaw.
When complete, Karangahape will be New Zealand’s deepest underground station at up to 35 metres underground. The station will be 217 metres long to accommodate nine-car trains.
Here the tunnel boring machine will arrive after carving out the twin tunnels from Mt Eden Station.
To ensure construction and earth mining noises are limited, a unique acoustically insulated noise enclosure will encase the access shaft.
“The noise enclosure is a bit like a silencer on a car, reducing the impact of construction at street level in a busy part of the city around Karangahape Road,” Burtenshaw said. “The enclosure muffles construction noise and gives us the flexibility to work longer hours to get the job underground done without disturbing neighbours living and working around us.”
Other work such as the installation of reinforced concrete panels are also underway along with utilities relocation. Plunge columns through the centre of Beresford Square are also beginning to be installed to support floor slabs during construction.