Waterview construction resumes after faulty concrete delay

Construction is due to resume at the weekend on the giant Waterview motorway interchange project after the discovery of faulty concrete forced it to a halt a fortnight ago.

The Transport Agency says detailed investigations have cleared the way for work to continue from Sunday night on the project's longest and highest traffic ramp.

Highways manager Brett Gliddon said tonight the weekend work would involve preparations for a large gantry to lift a multitude of beams into place, for the ramp to span the Northwestern Motorway.

The $1.4 billion Waterview Connection project is the highest profile of 70 casualities of weak, substandard concrete delivered to construction sites around New Zealand by Fletcher Building subsidiary Firth.

But Mr Gliddon said the faulty concrete, which Fletcher announced last week it had discovered during testing, was not located on sections of the ramp spanning the motorway or its existing interchange.

An affected span stops short of the motorway, and repairs will take place in stages before being completed once the full ramp is in place at the end of this year.

Mr Gliddon said there would be no risk to motorists or workers from resuming construction.

"There is no relaxation of safety or design standards," he said.

"Detailed investigations show we can resume construction without putting either the safety of people - those driving below the ramp or our workers - or the quality of our construction work at risk."

The first of 11 "Super T" beams, weighing between 55 and 65 tonnes, will be lifted into place by a large gantry on Wednesday night.

One more will be lifted each night until two new spans cross above the Northwestern Motorway.

Mr Gliddon said there would be full or partial closures of the motorway each night of the operation, starting with Sunday's preparatory work.

The lifting gantry's load would be shouldered by other sections of the ramp which he assured motorists were fully compliant with strength and durability requirements.

"As well, there will be additional strength from the temporary support structures we have in place during our big concrete pours on the interchange."

Although defective concrete would be removed from the deck of the affected span once the two new sections were in place above the motorway, the final repairs to a cross-beam would not be completed until the rest of the ramp was finished.

Mr Gliddon said the project, which includes a pair of motorway tunnels under Mt Albert, remained on track to be open to traffic in early 2017.

The affected Ramp 4 will ultimately extend 501 metres and rise 23m above the ground to carry two lanes of tunnel traffic towards downtown Auckland.