Westminster Magistrates Court heard how a member of the public was waiting for a bus on York Road, London in September 2008 when she was hit by the machinery being lifted to the fifth floor of a nearby office block.

The woman suffered severe multiple injuries including several broken bones and cuts and swelling to her head. She was in hospital for eight days and the injuries have affected her work and studies.

The building was being refurbished and instead of traditional scaffolding being used on the site, a mast climber had been erected, which allowed workers to be raised and lowered on the outside of the building.

The HSE investigation found that a crane and lifting slings were being used to lift a 380kg, 0.6m square by 2m high, air handling unit.

The crane was not fitted correctly and during the lift, the unit hit a mast climber and was knocked out of its sling causing it to fall from height and hit the member of the public.

After the hearing, HSE Inspector Bose Ogunsekan said: “Concentra Ltd failed in its duty to manage the safety of persons affected by its activities.

“A high risk activity such as using a crane to lift this sort of load on the site should have been fully risk assessed during the planning stages of the project.

“In addition, further measures that would have also protected members of the public from site traffic, such as an alternative pedestrian route and a temporary bus stop elsewhere, could have prevented injury to passers by.”

Concentra Ltd of High Street, Waltham Cross, Hertfordshire, EN8 7D, were found guilty of breaching Section 3(1) of the Health and Safety. at Work Act 1974 in relation to the incident. The firm was fined £20,000 and ordered to pay costs of £21,000.