Engineer: Don’t say safe
A structural engineer who inspected the Canterbury Television building after the September 2010 quake is still haunted by memories of the assessment, saying he keeps ‘‘wondering whether there was anything I missed’’.
David Coatsworth, a senior structural engineer for CPG New Zealand, yesterday gave evidence at a royal commission hearing into the CTV building’s failure.
He was the only engineer to inspect the CTV building after the quake, and he found there was no significant structural damage that would warrant it being closed.
However, he was adamant he never said the building was ‘‘safe’’.
Struggling to hold back tears, Mr Coatsworth told the inquiry he had relived the inspection ‘‘over and over’’.
‘‘I have asked myself whether there was anything I could or should have done differently that might have changed the outcome. In the end, I have to fall back on my professional judgment as an engineer,’’ he said.
He said his inspection after the September 4 quake was arranged during a phone conversation with CTV building manager John Drew. Unable to obtain structural design drawings from Mr Drew or Christchurch City Council, Mr Coatsworth carried out a visual inspection of the building.
The building had already been green-stickered after a level 2 rapid inspection by three council building inspectors.
Mr Coatsworth’s priority was to look for cracks and other evidence that structural elements had ‘‘yielded’’ in the September quake.
Mr Coatsworth observed that there was some ‘‘eccentricity’’ to the building design and noticed cracking damage on several levels, but he saw no evidence that the structural integrity of the columns and beams had been compromised.
Mr Coatsworth did not recommend a more detailed and expensive structural assessment. If there was hidden structural damage, there would be visible evidence of that, he said.
Because the CTV building was designed after the 1980s, he considered it unlikely it would be quake-prone.
In his report, which Mr Coatsworth emailed to Mr Drew on October 8, 2010, he said the building had performed well in the September quake.
Mr Coatsworth made recommenda- tions for repairs to the cracks in the concrete and also to plaster he found falling off the ends of concrete beams.
He carried out a further inspection on October 19 after a request from Mr Drew after an aftershock and came to the same conclusion. Mr Coatsworth conceded he had no idea how the CTV building would perform in another quake of the same magnitude as the September 4 quake.
His approach had been to look at the building’s diminished capacity, rather than its seismic capacity.
Questioned by lawyer Willie Palmer, for Alan Reay Consultants, Mr Coatsworth accepted that a layman like Mr Drew might misconstrue that if a building had not been damaged it meant it was safe.
‘‘As an engineer, I do not use the word ‘safe’. It is simply not possible to say a building is safe under all circumstances.’’ He never followed up on the recommended repairs.