Cellphone tower boosters have just begun operating and white lane lines are about to be painted on new black asphalt in New Zealand's longest road tunnel project.

Brent Gliddon, NZ Transport Agency highway manager and Iain Simmons, Well-Connected Alliance project manager, today showed off first the north-bound, then the south-bound tunnels of the $1.4 billion Waterview Connection, New Zealand's largest roading project.

Emergency and safety services are now being tested and a section of the new deluge system - where water is suddenly dumped into points along the tunnels to stop fire - was operated this morning.

The cell tower boosters were only turned on a few days ago and when the Herald visited this morning, all the bars on a Spark mobile were loaded. Reception is important for hands-free cell reception and motor vehicle passengers.

Advertisement

The Waterview Connection is due to open in April and NZTA said today the project was on track.

The current fit-out work includes compacting 74,500 cubic metres of aggregate for backfill, laying almost 5km of drainage pipes, installing 104 flame traps and applying 140,000sq m of paint: black on the roof so drivers are not distracted and what's above them just disappears, and cream on the walls for high visibility.

Tunnel Two the Northern Tunnel of the Waterview of the tunnel project. Photo / Greg Bowker
Tunnel Two the Northern Tunnel of the Waterview of the tunnel project. Photo / Greg Bowker

About 4000 lights have also been installed, 62 ventilation fans are within the tunnels, 50km of cable trays support wires and other equipment, CCTV cameras and signage is up and the five water deluge storage tanks are being tested.

Those tanks are at the Owarika or southern end of the project, above the south-bound tunnel's exit but disguised behind a wall above that exit.

The deluge system spews out water at 173 zones of the tunnels. Each zone has been developed every 30m and the pressure is so great, that vast plumes of water quickly flood the asphalt, sending up fine spray mist to the tunnel roof.

Testing and commissioning of the safety systems is now well under way after asphalt went down in each of the 2.4km long tunnels, twice as long as the Auckland Harbour Bridge.

A view from one of the over passes looking over the motorway at the Waterview Connection Project. Photo / Greg Bowker
A view from one of the over passes looking over the motorway at the Waterview Connection Project. Photo / Greg Bowker

But a spokesperson said just because the project was nearing completion and looked almost finished, it did not mean it was ready for motorists. All the safety equipment needed to be tested first, the spokesperson emphasised.

Three lanes, each 3.5m wide, have been built in the tunnels, which are 6m below ground at their most shallow point but 45m at the deepest.

"The detailed and comprehensive commissioning programme is testing all equipment, installed in the tunnels to ensure they are working correctly and the tunnels are safe to open," an NZTA statement said.

A walk through the project revealed a steep gradient in parts: 5 per cent at the steepest point, compared to the bridge's 8 per cent, Simmons said.

Eighteen cross passages or chambers are operational and these are large rooms between the tunnels which can be used in an emergency, house equipment and not only allowing escape from one tunnel to another but also a safe point for people in an emergency.

All the concrete beams on the Great North Road interchange have now been installed and asphalt has been laid on four ramps. The final job will be asphalting motorway connections at the Owarika or southern end and the Waterview or northern end.

Tunnelling work started in 2013, with the first tunnel completed in 2014 and the second on October 19 last year.

A public open day is planned some time next year but the date has not yet been announced.