Engineers who declared PGC building safe defend decision

Fire Service personnel look for survivors in the collapsed PGC building on Cambridge Terrace. Photo / Geoff Sloan

The boss of two engineers who inspected Christchurch's Pyne Gould Corporation (PGC) building after a magnitude 7.1 earthquake and concluded it was "safe to occupy" today backed their judgement.

Workers inside the 48-year-old PGC building had raised safety fears after finding cracks in its columns and a main load-bearing wall after the jolt on September 4 last year.

It was inspected four times by Holmes Consulting Group (HCG) Ltd engineers and deemed safe on each occasion leading up to the fatal February 22 quake, which resulted in the building's collapse and the deaths of 18 people.

HCG director John Hare told the Royal Commission hearings into the Canterbury Earthquakes today that he would have reached the same conclusions as his two engineers who gave evidence last week.

Structural engineers Mark Whiteside and Alistair Boys inspected the building four times between them between September 7 last year and February this year and concluded each time that it was "safe to occupy".

They were questioned by commission lawyer Marcus Elliott on why they ignored previous HCG reports that deemed the building as having "severe weakness seismically" and being "earthquake prone".

The pair said they were instructed to carry out basic, Level Two assessments, which were a quick, visual inspection of the building to determine if it had been significantly weakened by quake damage.

Today Mr Hare backed his engineers' conclusions, and said he would have done the same thing.

He said that referring to old reports would simply have been "irrelevant" to their task.

Stephen Mills QC, counsel assisting the commission, asked Hare to put himself in his engineers' shoes and asked what he would've done in that same situation, bearing in mind information in the 1997 and 2007 HCG reports, as well as safety concerns raised by PGC tenants.

Mr Hare, president of Structural Engineering Society New Zealand and who is currently seconded to Canterbury Earthquake Recovery Authority (Cera) as its acting principal engineer and adviser, said: "Engineers were inspecting many buildings, some of which information might have existed for, and so the standard instruction to all, and my approach would have been the same, was that at all stages when entering a building to make sure we can identify the structural system so we can figure out what's holding it up and what is critical.

"Regardless of information that people think they have or think they know about the building, the important thing is not to have pre-conceived notions ... but to use your eyes, observations and engineer's judgement to determine whether the building capacity had been diminished, which was what we were searching for."

He said that historic information was "almost a sideline" and that the important thing was to identify was how the building had performed in the last shake.

Warnings the PGC was "potentially earthquake prone" was "irrelevant" to their inspections, Mr Hare said.

However, he did accept that "with hindsight", a detailed assessment - which included a more invasive investigation of the building and its history - is what should have been instructed by the building owner.

The latest phase of the Royal Commission hearings into the Canterbury earthquakes, which is focusing solely on the collapse of the PGC building in the centre of Christchurch, continues.

The hearing is due to conclude tomorrow with an expert panel discussion.