He suffered cuts and bruising to his face in the assault and his glasses were so badly damaged that he could not drive away – prompting several hours of tailbacks over rush hour.
The 53-year-old was driving his Yodel van west when he undertook a silver Mitsubishi Shogun.
When the van stopped in traffic near the Lothianburn junction, a man who had been driving the Shogun jumped out of the car.
He assaulted the van driver before getting back in the vehicle and continuing along the westbound carriageway.
The incident, which happened at around 4.30pm on Friday, prompted long hold-ups on the A720 as the van was left stationary, blocking the outside lane.
Police investigating the incident are now urging any witnesses to come forward.
Constable Declan Fitzpatrick, of the Road Policing Unit, said: “We are appealing for anyone who witnessed the assault of the van driver, or has further information on the driver of the Shogun, to come forward to police. This incident ultimately caused considerable disruption to traffic on a Friday afternoon, while the victim received minor cuts and bruising to his face. Those with information should contact Police Scotland on 101.”
Neil Greig, of the Institute of Advanced Motorists (IAM), said the incident was concerning. He said: “Violent road rage is thankfully very rare. All the research I have seen on it suggested that there’s a lot of finger pointing and shouting that goes on every day. But in terms of descending into violence, that is rare.
“You never know how the person next to you is going to react, if you lose control of a situation. You never know what’s going to happen. Our advice is not to react to things.”
He advised drivers who feel threatened by other road users’ actions to drive to a police station or stop in a public place to report any incidents.
Mr Greig said: “We welcome the police trying to find this person and making this a top priority. This is an assault and should be treated as a very serious offence. Hopefully they will face the full force of the law.”
Last year, the Evening News revealed how a two-year-old girl was left “distraught” when a lorry driver leapt from his cab and confronted her family.
The trucker, who was at the wheel of a Carr’s Flour Mills vehicle, reacted after he was beeped at for nearly crashing into an overtaking car. He began gesturing out of his window before later stopping, jumping out of the lorry and opening the car door and swearing.
A couple and their young daughter were travelling in the car on the A90 towards the Forth Road Bridge in October, and captured the drama on camera.
A recent survey by online comparison site confused.com found that more than a third of motorists – 37 per cent – had been involved in a road-rage incident.
The study, which was released earlier this year, also revealed that nearly a fifth admitted being involved in an incident which led to a physical altercation.
Yodel was unavailable for comment.