Richard Chodkiewicz, 53, was working on a lift installation for a new Radisson Blu hotel in Bristol, when the half-metre length of scaffold pole struck him in July 2008.

Chodkiewicz and a colleague were at the bottom of the lift shaft. Another man 18 stories up was lifting the 3.7kg section of pole on a piano wire to use as a plumb line to help align the lifts. But the tube slipped the tie, struck Chodkiewicz, and left the father of two needing round-the-clock care.

Miller Construction, which was running the project, was fined £40,000 at Bristol Crown Court. The engineer’s employer Somerset-based contractor Hoistway was fined £70,000.

Both firms had previously admitted breaches of health and safety regulations.

A HSE investigation found that there had been inadequate site management and insufficient risk assessments carried out before the work was undertaken. Openings had been left unguarded and not enough had been done on the site to prevent the risk of falling objects.

Steve Frain, HSE Inspector, said: “The contractors involved should have had effective arrangements in place to ensure that Mr Chodkiewicz was not in the bottom of the lift shaft while anything was being raised or lowered.

“Even a smaller object falling on him from that height could have killed him or his colleagues.

“As it was, he was struck with such force by the pole that he now has severe brain damage and requires 24-hour care.”