An HSE investigation found that Gary Draper was using his mobile phone while operating the excavator vehicle on a site in Milton Keynes and had not noticed his colleague.

Milton Keynes Magistrates’ Court heard that Draper had been operating the excavator at the Middleton site on 8 December 2012, working alongside a colleague who was driving the site dumper truck.

The operation involved Draper excavating and dumping material into the truck for transport to another location at the site.

The court heard that the driver of the dumper truck, who does not wish to be named, had returned to the excavation site to await the next load of material.

Draper had been using his mobile phone and, not realising his colleague had returned, rotated the upper body of the excavator causing the metal bucket to strike the driver on the side of his head.

The worker sustained multiple fractures to his jaw as well as a punctured and collapsed lung.

He was hospitalised for ten days and did not return to work until 14 months later, and will require further surgery on his jaw.

Gary Draper, of Rushden, Northants, was ordered to pay compensation of £2,500 to the injured worker, and costs of £1,554 after pleading guilty to a single safety breach.

Speaking after the hearing, HSE Inspector Stephen Manley said: “Construction site vehicles are extremely powerful and, if the operator becomes distracted, can be highly dangerous.

“Road users are rightly banned from using mobile phones when driving cars.

“It’s clearly important that those in control of machinery – weighing up to 40 tonnes in some cases – need to be equally attentive and concentrate solely on the job at hand.

“This incident could easily have been avoided if the operator had followed site rules and not become complacent about his responsibilities when operating his vehicle.”