HSE investigators still don't know why a Canary Wharf tower crane collapsed killing three workers. To make sure it never happens again, new rules and guidelines need to be put in place as soon as possible.
Despite three years of investigation it is still not clear what caused the fatal collapse of tower crane TC-3 at Canary Wharf in 2000. In the inquest into the deaths of the three crane erectors the jury at St Pancras Coroner's Court in central London returned an open verdict this week. The Health and Safety Executive has admitted that the technical cause of the accident may never be established.

The collapse happened as the erection team were increasing the height of the tower crane by adding another section using a "climbing frame". For some reason the frame twisted during this operation causing the top of the 450ft crane to break away.

Whatever the cause of the collapse it will still have far reaching consequences for both plant hire and crane use. The rules will be tightened for crane design and operation and plant hire contracts will also have to change to make it clear who is responsible for operating plant.

The Health and Safety Executive has already said it will introduce new guidance on design, use and maintenance of climbing frames on tower cranes. It launched a discussion document at the beginning of the year on the safe use of cranes. It called on contractors to carry out detailed risk assessments that take account of local conditions. The HSE says, though, that the document was not related to the Canary Wharf collapse or any other incident.

The document calls on contractors to assess how falls from walkways, platforms and access ladders can be prevented. It says that measures are needed to ensure that slewing of the crane jib does not happen during a climb. Kevin Myers, the HSE's chief construction inspector said that the document should lead to more robust standards for this type of work. European and British standards for the manufacture of tower cranes' climbing frames and their operation are also being written.

During the inquest the jury heard that there was no plug fitted to the electromagnetic break to prevent the jib from slewing while sections were put in place. There was also no anemometer to measure wind speed, although the weather conditions on that day were still.

Earlier this year the High Court found crane hire company Hewden Tower Cranes to be responsible for controlling the equipment at the time of the accident. As a result Hewden Stuart, which has now sold its crane business, could face damages of £8m.

The High Court ruled that Hewden was responsible rather than the crane-operator Cleveland Bridge because an industry wide contract agreement states that the erection and dismantling of cranes is the responsibility of the hire company. The judge said this extends to the operation of the crane equipment. Hewden claimed that climbing should be treated as a normal operation for which the hirer was responsible.

The decision means that the CPA model conditions contract, which is used for standard plant hire contracts, will now have to be revised. Martin Scott, a partner at Walker Morris solicitors, said that operations carried out by crane hirers after equipment erection would now have to be included in contracts.

The end of the HSE inquest means that a postponed research project into crane safety can now go ahead. Funding from the DTI for the project managed by the Construction Industry Research & Information Association (CIRIA) was put on hold until the HSE inquest was completed.