THE HEALTH and Safety Executive has admitted it may never discover what caused the Canary Wharf crane collapse which killed three workers.
Kevin Myers, the HSE's chief inspector of construction, said the threeyear investigation may not provide an exact answer into how the top of the self-climbing tower crane came down during what should have been a routine jacking operation.
He said: 'It's our responsibility to continue to investigate and ensure no stone is left unturned. But there is a possibility we will not be able to say what exactly happened on that day.'
The admission is a bitter blow to relatives' hopes of finding out what caused the tragedy and the possibility of any legal action.
Caroline Clark, the sister of 33-year-old Londoner Peter Clark, who died in the tragedy, said: 'It's devastating that after nearly three years of investigating the HSE is still no nearer finding out how the crane came down. If it can't explain how the crane collapsed, how is it going to stop it happening again?'
A HSE inquiry into how the 150tonne tower crane collapsed while in operation on the HSBC skyscraper in May 2000 continues and a preliminary report was sent to Poplar Coroner's Court in east London last month.
A hearing date has yet to be set and is understood to be held up by a backlog of cases.
But Mr Myers said inquiries will continue and evidence presented during the coroner's inquest could shed new light on the HSE's case.
He added: 'This is not a straightforward forensic and technical investigation. We have not been able to reconcile the technical investigation with the evidence gathered from witnesses. It's more technically challenging than many other investigations we have carried out.
That is why it is taking so long.'
As well as Mr Clark, the collapse of the German-made Wolff Hydro 32BF crane, which was on hire from Hewden Stuart, claimed the lives of Martin Burgess, 31, of Castleford, West Yorkshire, and Michael Whittard, 39, from Leeds.
The comments came as the HSE released a discussion document this week on the safe use of climbing frames on tower cranes, prompted by the Canary Wharf tragedy.
It follows concerns of the potential for serious accidents during the assembly, use and dismantling of external climbing frames.
Responses to the discussion document, which must be returned to the HSE by May 16, are expected to be incorporated into a set of guidelines and standards on the use of tower cranes.
Mr Myers said: 'There are potential hazards not fully recognised by designers, manufacturers and users in regard to the use of this type of equipment.
'This document should help with the development of more robust standards for this type of work and hopefully reduce risk.'
He added that the suggestions put forward in the document are not directly related to the Canary Wharf incident.
Designers must take into account all the relevant physical forces
Information available to the erection supervisor during climbing needs to be improved
Measures to avoid deliberate or inadvertent slewing of the crane jib during climb must be more effective
Prevention of falls from walkways, platforms and access ladders needs some thought
Operating instructions should be easily understood and cover all the critical steps
Consideration should be given to the certification of erection crews, manufactures or suppliers of climbing frames
Detailed risk assessments, taking account of local conditions, should be carried out
Consideration should be given to how the overall climbing operation is to be supervised
A systematic approach to the examination, test and maintenance of climbing frames is needed
Establish and maintain the balance of the crane during changing environmental conditions
Correct location of the climbing frame on the lugs or other support points during the climb
Prevent slewing - either deliberate or inadvertent
Be aware of risks in relation to wind speed