On Sunday 21 May 2000, two crane erectors and a crane driver died when the top of a tower crane erected at a construction site in Canada Square, London E14 overturned and fell about 120 metres to the ground
The tower crane, one of several on the site, was being ‘climbed’ by a team of erectors to increase its height. This was achieved by adding crane mast sections using externally mounted climbing equipment that consisted of a nine metre high ‘climbing frame’ incorporating a long stroke hydraulic cylinder. The erectors were close to finishing the final ‘climb’ when one of them suddenly became aware that a wheel guiding the climbing frame was twisting and distorting sideways. The mast started to shake violently and then the ‘climbing frame’, hydraulic cylinder, new mast section and the top of the crane overturned.
The Health and Safety Executive investigation of this terrible incident was undertaken jointly with the Metropolitan Police, (in line with the protocol on ‘Work-Related Death’) and involved staff from the Health and Safety Laboratory (HSL) and an HSE lifting specialist. Advice was obtained from various specialists including the Building Research Establishment (BRE), a Professor of engineering and a tower crane consultant recommended by the Occupational Safety and Health Administration of the USA. HSE explored the evidence extensively and weighed up various possible causes but it has not proved possible to reach a convincing explanation for the precise cause of the collapse. Although specialist engineers put forward four different hypotheses none fitted the witness and physical evidence sufficiently closely to provide a compelling explanation for the collapse of the crane.
Having considered the available evidence and the specialists’ reports, and taken legal advice, HSE has concluded that there is insufficient evidence to support criminal proceedings in respect of this fatal incident. Although HSE has been unable to establish why the collapse occurred it has identified a number of actions that crane designers, manufacturers, suppliers and users could take to minimise the risk of further incidents. In 2003, HSE released a discussion paper to publicise this advice. Work has also been undertaken with the British Standards Committee dealing with cranes to revise the Tower Crane standard and with others to promote better training and information. This report builds on the discussion paper by explaining the factors considered during the HSE investigation and how risks that may arise should be controlled or managed.