TWO engineering firms are to be prosecuted following the deaths of four workmen who fell from a motorway bridge, the Health and Safety Executive said yesterday.

The men died after falling 80ft from the M5 Avonmouth Bridge at Portway, near Bristol, when the platform they were working from came off its rails in high winds, on September 8 last year.

The four, Paul Stewart, 23, of Newcastle, Andy Rodgers, 40, of Coulby Newham, Middlesbrough, Ronald Hill, 38, of Baillieston, Glasgow, and Jeff Williams, 42, of Newport, South Wales, had been installing a runway beam to carry a maintenance gantry when the accident happened.

Yarm Road Ltd, which was formerly known as Kvaerner Cleveland Bridge Ltd, is being charged with a breach of the Health and Safety at Work Act 1974 for ''allegedly failing to ensure that persons not in its employment, including Ronald Hill, were not exposed to risks to their health and safety".

The firm, which is based in London, is also being charged with breaching another section of the Act for ''allegedly failing to ensure the health and safety of its employees, including Jeff Williams, Paul Stewart and Andrew Rogers, while working from underslung access gantries to undertake strengthening and runway beam replacement work".

Costain Ltd, of Maidenhead, Berks, is being charged with a breach of the Act for failing to ensure the four men, who were not employed by the firm, were not exposed to risks to their health and safety.

The maximum fine for each offence is £20,000, unless magistrates decide to refer it to crown court.

The case is due to be heard at Flax Bourton Magistrates' Court, in north Somerset, on January 26