Victoria Park tunnel at halfway point

Troy Butcher's digger breaks down a wall to link two sections of trench in the new Victoria Park motorway tunnel. Photo / Natalie Slade

It was hole-through time for Auckland's $406 million Victoria Park motorway tunnel project yesterday when a digging machine knocked down an earthen wall to link two large sections of trench.

As traffic passed overhead in Beaumont St, above 30-tonne concrete roof beams straddling the motorway trench, digger driver Troy Butcher's machine emerged through the top of the wall before he started bringing it down with his bucket.

The removal of the wall, at the boundary between a rocky former headland and what used to be the Freemans Bay inlet before the late 19th century land reclamation which became Victoria Park, has made it possible for workers to walk 300m along the tunnel trench.

That is two-thirds of the 450m length of the "cut-and-cover" tunnel which is being dug under the park to an average depth of eight metres (and a maximum of 13m) to provide three northbound motorway lanes, leaving all four lanes of the overhead viaduct available for southbound traffic from 2012.

The trench will be covered with 360 roof beams, of which about 170 are in place.

Transport Agency highways manager Tommy Parker, who inspected the trench yesterday, said the hole-through signalled the halfway point for building the tunnel.

Although tunnel construction is expected to be completed by April, it will take most of next year to fit the structure with lighting, communications and firefighting systems including roof sprinklers and emergency exits.

"The fit-out is a very substantial part of the process - it will be under way by Christmas and is likely to take the best part of a year," Mr Parker said.

With a very large hole in the ground through Victoria Park and at the Fanshawe St motorway on-ramp, motorists are now able to see what they are getting in terms of increased motorway capacity.

But Mr Parker said the view would be fleeting, as the hole was being covered over almost as fast as it was appearing.

Construction manager Mike Wall said the sprinkler systems would be built to a high standard as trucks carrying volatile or inflammable loads would be allowed to use the tunnel, unlike the Northern Gateway toll road's tunnel, which they must bypass.

A subdivision wall will also be built along the western side of the tunnel to provide a fire-proof escape route.

Tunnel construction superintendent Callum McCorquodale said yesterday's hole-through would help to boost the morale of workers, who had toiled through a wet and bleak winter to keep the project well on schedule.

Another project milestone was reached on Sunday night when the Victoria St West end of Franklin Rd was realigned close to its original position, but now running over tunnel roof slabs.

Victoria St West has also been restored to its original alignment.

But the Transport Agency has decided to delay until the middle of next month the reopening of the Wellington St motorway on-ramp, which has been closed since late August for construction work on the southern approach to the new tunnel.

Although the ramp was to reopen tomorrow, the delay is needed to give Auckland Transport time to install a pedestrian crossing signals across the top of it, primarily for the safety of children from nearby Freemans Bay School.

Mr Parker said his organisation was happy to agree to Auckland Transport's request to meet long-time concerns about the safety of youngsters walking between the central business district and the school, "weaving" among moving vehicles to get across the ramp.