A top engineer behind Christchurch's post-earthquake building assessments fronted up yesterday to explain the much-criticised inspection system and propose changes for future disaster plans.
The city council's handling of post-quake building inspections has come under fire during the Canterbury Earthquakes Royal Commission hearings, which began in October.
Families have questioned why some buildings, especially the PGC and CTV structures, were green-stickered and not examined more closely after the initial quakes of 2010 before the killer jolt came on February 22, 2011.
Yesterday, structural engineer Dave Brunsdon of Kestrel Group told the commission where inspection guidelines could be improved.
Mr Brunsdon, an expert in infrastructure risk management and emergency response management, has been responsible for New Zealand's post-disaster building safety evaluation and rescue engineering arrangements.
He explained that New Zealand's post-disaster building evaluation process was based on international best practice, but was "far less developed" than in the US and Japan when the September 2010 quake hit.
He helped Christchurch City Council co-ordinate its inspections after the magnitude 7.1 shake of September 4, 2010, which sparked the Canterbury earthquake sequence. The placarding process and the use of green, yellow and red stickers, designed by the New Zealand Society for Earthquake Engineering, was confusing for the public and building owners and had never been used on a major scale before, he said.
After the Canterbury disaster, the process would need revision to iron out its "shortcomings and gaps".
Councils across New Zealand needed to clarify phrases like "occupiable" and "useable", and better explain the concept of "interim occupancy" after natural disasters.
A key recommendation was a requirement for owners of inspected placarded buildings to "move swiftly" to get their own detailed engineer evaluations undertaken.
He proposed the introduction of a white sticker during this period, because of the implied safe connotations of a green sticker.
Mr Brunsdon was also quizzed by the commission on the danger of unreinforced masonry (URM) buildings. He said many of the Christchurch quake issues were not necessarily with buildings collapsing into themselves, but with blocks, masonry and parapets falling from URMs into the street.
The issue of cordons and road closures would have to be examined to increase public safety, as would the need for an increased priority in restraining masonry parapets.
Mr Brunsdon was the first witness in a two-day hearing into how buildings are assessed after earthquakes. Academics, engineers, council officials and professional engineering societies will discuss today how buildings should be managed in the immediate aftermath of a disaster.
They will also look at the evaluation of building safety after the earthquakes and how the system can be improved.
The hearing comes after an eight-week probe into the CTV building collapse in the February 2011 quake which claimed 115 lives.
Closing submissions from counsel assisting the commission and affected parties who wish to be heard are due tomorrow and Thursday.
SECOND ANNIVERSARY PAUSE
Christchurch will pause and reflect today on the second anniversary of the magnitude-7.1 earthquake that marked the beginning of the city's seismic ordeal.
Incredibly, it resulted in no deaths - largely attributed to the 4.35am time it struck - and many residents thought they had escaped unscathed.
But as the days and months went by the region kept moving, the shakes culminating in the shallower 6.3-magnitude quake of February 22 last year, which claimed 185 lives.
In the past two years, as the rattled city has tried to pick itself up and put itself back together again, the aftershocks have continued, and now total a staggering 11,923.
Hundreds of buildings have been demolished, billions of dollars in insurance and government cash has been paid to owners of damaged houses and businesses.
But many residents are still fighting the same fight two years on.