Larry Newman, 37, was part of a team sent out by subsidiary firm Balfour Beatty Civil Engineering to install temporary traffic management measures and repair a barrier that had been damaged in a collision on the A2 road.
The crew deployed a lorry-mounted crane to remove a post footing that had snapped. During the work, the crane became unstable and swung backwards, hitting Newman on the head and killing him. He was pronounced dead at the scene.
Balfour Beatty Civil Engineering admitted offences under Sections 2(1) and 3(1) of the Health and Safety at Work Act and must pay £14,977 in costs.
Andrew Cousins, a Health and Safety Executive inspector, said this "entirely preventable" incident was down to a lack of a safe system of work and could have been avoided with the use of a "suitably sized excavator -¦ to remove the footing mechanically".