Birse Civils and Serco must pay over £400,000 in fines and costs after admitting they failed to protect 42-year-old Cecil Grant who fell to his death while working over the M5 motorway near Clevedon.
Mr Grant, from Southmead Bristol, was repairing CCTV cameras during the incident on 24 January 2006, when he fell off a wall into bushes 12 metres below, suffering serious injuries.
He was taken to hospital and died of his injuries ten days later.
At a hearing at Bristol Crown Court Mr Grant’s employer Serco pleaded guilty to working at height regulations and health and safety management regulations.
It was fined £200,000 and ordered to pay costs of £36,186.
Principal contractor Birse Civils also pleaded guilty and was fined £100,000 with costs of £180,093.
HSE inspector Steve Frain said: “There were major failings in the way this work was planned which sadly resulted in Mr Grant’s tragic death.
“When employees are working at height, proper plans must be put in place and workers made aware of possible risks.
“In this case, Mr Grant had not been made aware of the dangerous drop where he was working. If he had been, a tragic incident could easily have been avoided.”