A driver is facing a lengthy jail term for causing a lorry carrying a 60-tonne load to flip over – after deliberately crashing in to it.

Craig Thomson drove his Vauxhall Australia straight in to the path of the Scania HGV just outside Luss in the middle of the afternoon one day in October.

The force of the crash caused the HGV, which was carrying four 15-tonne ballast plates and was being driven by Paul Singer, to career out of control and flip on to its roof, trapping Singer in the vehicle.

It took 40 minutes for fire crews to cut Singer and Thomson from the wreckage of their respective vehicles, while two of the ballast plates blocked the carriageway and the other two blocked a layby.

The details emerged this week when Thomson, 35, appeared in the dock at Dumbarton Sheriff Court to admit his guilt over the incident.

He pleaded guilty to driving dangerously and causing Singer serious injury on October 10 this year.

Procurator Fiscal Depute David McDonald explained: "The accused parked his Vauxhall Astra in a layby off the northbound carriageway on the A82, one mile north of Luss.

"Paul Singer was driving his Scania HGV southbound.

"Mr singer's vehicle was carrying a load of crane ballast which was approximately 60-tonnes for the load plus the weight of the tractor and trailer.

"As he approached the layby the silver Vauxhall Astra drove straight out and in to the front of Mr singer's HGV.

"Mr Singer made attempts to swerve to avoid the accuseds vehicle and a head on collision and brakes and served violently to the nearside as the vehicles impacted offside to offside.

"The sheer weight and momentum of the HGV caused it to continue southbound whilst violently put of control."

Singer's 60-tonne load was thrown from the vehicle and his lorry then flipped over, coming to a rest in the layby.

Officers raced to the scene to investigate and found both drivers trapped in their vehicles.

They then spoke to Thomson who said: "it didn't work, I'm still here."

Both men were taken to hospital for treatment, with singer having suffered two broken ribs, a punctured lung and a dislocated shoulder, while medics stapled a cut to Thomsons head.

Sheriff William Gallacher slammed Thomsons for his actions on the day in question and remanded him in custody ahead of sentencing.

As he did so, he said: "I don't pretend to understand the reason why you chose to do this in your own mind.

"it was an act of almost unmitigating wickedness which could have been catastrophic for you and others."

Thomson will be assessed by social workers ahead of sentencing and is due to learn his date later this month.