Christopher Lewis was carrying out fencing work close to the Holmesdale Tunnel section of the M25 near Enfield when he was crushed between a van and a safety barrier after a lorry jack-knifed on the motorway.
Carillion was carrying out repairs to overhead lighting in the tunnel at the time of the tragedy in August 2004.
Carillion arranged with subcontractor Traffic Management (North East) Limited to set up an overnight contraflow.
CD Fencing and Construction Services Limited were removing and restoring wire rope safety fencing in the central reservation.
Southwark Crown Court heard after the repair work had been completed, Lewis and colleague Simon Reid, both employees of CD Fencing, were in a closed lane waiting to reinstate the safety fencing so the traffic management equipment could be removed, allowing the tunnel to re-open.
Lewis and his colleague were preparing their materials and equipment for the task when a lorry jack-knifed in the contraflow system.
The lorry hit cones and a stationary CD Fencing van, sending the van careering towards the hard shoulder. The lorry passed within a metre of Reid.
Lewis was later found pinned between the van and a safety barrier at the rear of the hard shoulder. He was pronounced dead at the scene. Gavin Shaw, an employee of TMNE, was knocked over by a traffic cone and suffered a broken wrist.
Carillion Highway Maintenance Limited pleaded guilty to a safety charge and was fined £200,000 with £50,000 costs.
Traffic Management (North East) Limited was also found guilty and fined £2,000 with costs of £120,000 but the company is in administration.
CD Fencing Ltd was formally acquitted of any charges and the driver of the lorry had been previously convicted of driving without due care and attention in a case brought by the Crown Prosecution Service.
After the hearing, HSE Principal Inspector Andy Beal said: “Although the lorry driver was not blameless, Carillion and TMNE failed to do enough to protect Mr. Lewis and others working in the road that night.
“Speed limits were too high, there was a poor cone layout through the contraflow and there was inadequate management of subcontractors.
“Had both firms met their legal responsibilities, this collision could have been avoided. The risks associated with work on high speed roads are well known and it is vital traffic management systems are correctly set up and well established safe guards are followed when people are working within them.”