Dialogue: Construction industry at fault for workers' deaths

So dangerous are the excavations at many construction sites around Auckland that tragic, and wholly preventable, accidents are inevitable, writes LAURIE WESLEY*.

Another tragic death has occurred because of the collapse of a clay bank on an Auckland construction site.

Although Occupational Safety and Health is still investigating the cause of this accident, the harsh reality is that many other building sites around the city are so dangerous that it is a wonder more deaths do not occur. It is, in fact, high time that the construction industry was called to heel and stopped engaging in sloppy and life-threatening practices.

I say this because of simple observation of contractors' activities on building sites. It is not at all difficult to discover construction sites in Auckland where grave risks are being taken with workers' lives.

Last year, for example, I came across a deep excavation in the inner city where repairs to some sort of services were being carried out. The excavation was 3m to 4m deep and a workman was busy at the bottom. The sides of the excavation were more or less vertical and consisted of heavy and wet clay. The sides were not supported in any way.

A collapse of the excavation could have occurred at any time and the worker would have been buried. I stopped and pointed this out to the workman's mates at street level. They seemed to agree with me but seemed unprepared to take action.

Some years ago, passing a construction site in Birkenhead, I noticed workmen laying pipes (or steel reinforcement) in a trench about 1m deep at the foot of a vertical clay bank 3m to 4m high. There was no support of the bank and it could have collapsed at any time without warning. The workmen's lives were in grave danger.

I sought out the site foreman to let him know my concern. He seemed somewhat uncertain about whether I knew what I was talking about, but to his credit immediately got the men out of the trench.

On neither of these sites did a tragedy happen, but it could so easily have done. In the light of this latest tragedy I have asked myself what additional steps I should have taken at these two sites.

A telephone call to OSH on this issue brought the expected reply that I should write a letter expressing my concern and, in due course, inspectors would look into the situation.

This, of course, could well be too late to achieve any useful purpose. As an OSH representative said after this latest tragedy, it was not the job of OSH to carry out safety inspections of construction sites. Responsibility for safety has been passed to the owners and builders.

I could also describe a number of other dangerous practices not involving clay banks that are common on construction sites. But I want to draw attention to the danger imposed by vertical or near-vertical clay banks. The cold, hard fact is that unsupported vertical clay banks are unpredictable and pose a serious threat to the lives of anyone working near them.

No one can give an assurance they will be stable. Nor can anyone predict when they will collapse. They may collapse without warning at any time.

The danger to workmen is even greater in unsupported trenches, as distinct from isolated banks. The collapse of a bank can sometimes push the worker sideways, giving him (or her) a lucky escape, but the collapse of one side of a trench pins the worker in place and crushes him against the other side.

Reports of the death of workmen from trench collapses are far too frequent. What is more, the statement often made after such events is along the lines of the trench having looked totally stable.

Site owners, developers, contractors and geotechnical engineers must recognise that vertical clay banks need to be supported by properly designed retaining devices before workers are allowed to undertake duties near them.

Perhaps those of us who teach geotechnical engineering have been at fault in not adequately getting this message across. In all events let's face up to these situations honestly, and let's not hear the childish nonsense that is often fed to the press after such events.

That, for example, the cause of the collapse is unknown but could have been rain or traffic vibrations. We all know that it rains in Auckland and we also know that streets are used by traffic that causes vibrations.

These are totally foreseeable factors to be taken into account in designing the support system, and cannot be used as excuses when things go wrong.

Ironically, this latest collapse took place across the road from the High Court, where a similar collapse happened not many years ago. Excavations for extensions were made alongside the foundations of the old building.

A collapse occurred which damaged the historic building but, fortunately, did not involve human casualties. Spokesmen who appeared in the media at the time expressed surprise at the collapse, saying they had no idea what caused it.

Casual inspection of the site from a distance, and pictures that appeared in the press, suggested a simple explanation - failure to provide support for the foundations when their support from the natural ground was removed.

Unless there is a lot more realism and honesty in facing up to the cause of these collapses, and the lessons from them are taken on board by the appropriate parties, it is a sad fact that predictable, and totally avoidable, tragedies will happen.

* Dr Laurie Wesley is a senior lecturer in geotechnical engineering at the University of Auckland.