A driver high on methamphetamine, who hurled a toolbox through a terrified woman’s car window and told her he would kill her, has been jailed for more than four years by a judge who described the attack as “utterly unprovoked” and “extreme”.

The extraordinary road rage attack, captured on dash cam, left the 43-year-old victim needing treatment for post-traumatic stress disorder, unable to sleep and worried about getting back behind the wheel.

Adam Nicholas Dennis, 30, was travelling so close to Tracey Leicester’s Hyundai i30 as she drove alone to the dentist in Morley in October 2016 that when she made a left turn, he had to swerve his Jeep to the other side of the road to avoid hitting her car.

Enraged by what District Court Judge Alan Troy described as an “imagined slight” by Mrs Leicester, Dennis followed her, swerving around her car before coming to an abrupt stop.

Camera Icon Adam Nicholas Dennis, 30, gets out of his car before throwing a tool box through the victim’s passenger window. Credit: Supplied.

Mrs Leicester was able to manoeuvre her car to get away.

But in dash cam footage obtained by The West Australian yesterday, Dennis is seen cutting Mrs Leicester off a second time before getting out of his four-wheel-drive holding a small yellow toolbox.

He launched a tirade of abuse before ripping off Mrs Leicester’s side mirror.

“This is how road rage happens,” Dennis can be heard saying. “F...ing dog. I’ll kill you, you c....”

Dennis drove away but with Mrs Leicester also driving off in the same direction, he mistakenly believed she was following him.

He again pulled up and got out of his car, and threw the toolbox through Mrs Leicester’s passenger side window, showering her in glass.

In the vision, Mrs Leicester can be heard crying. She is on the phone to her husband, telling him: “You need to help me, I’m on Camboon Road and I’m being attacked by a f...ing road rage toss pot”.

“I’ve got it all on dash cam, but he just smashed my window,” she said.

“I’m f...ing shaking like a leaf, hun, he’s just taken off. I’m coming back now, I don’t know what else to do ... I’m sh...ing myself.”

Judge Troy told Dennis that he had looked in vain for some sort of satisfactory explanation for his behaviour but said “you proffered no explanation for your conduct other than you were not in a good mood because you had had a bad day”.

“I find that your action was utterly unprovoked,” he said.

“Thankfully, this incident was captured on dash cam and it is a depressing feature of modern-day life, particularly in Western Australia, that motorists going about their lawful business increasingly need to invest in these devices so as to protect themselves and preserve evidence of conduct of this type, albeit your conduct I regard as extreme.”

Dennis claimed he was coming down off meth that day, but Judge Troy said it was clear he was significantly affected by the drug.

“In my view it is important that the courts send a clear message that anyone who voluntarily uses methamphetamine and, as a result, confronts a law-abiding member of the community and terrorises them in the way that you did will be dealt with with appropriate severity,” Judge Troy said.

Dennis was sentenced to four years and three months in jail.

It will not be his first stint behind bars.

He was jailed for four years in 2013 after he pleaded guilty to unlawfully killing his teenage brother Alex by unintentionally piercing his heart with a pair of scissors — which he had been using to cut up cannabis — during a fight.

His attack on Mrs Leicester happened 2½ months after completing his parole, with Dennis’ lawyer David Manera saying his client turned back to drugs to numb the pain he felt over his brother’s death.

Mr Manera said Dennis was remorseful and admitted his behaviour was “unacceptable and outrageous”.

Dennis pleaded guilty to with intent to harm, doing an act as a result of which the life, health or safety of the victim was or was likely to be endangered, and unlawful damage.

His sentence was backdated to July 5 last year. He was made eligible for parole.

The West Australian’s recent Zero Excuses survey of more than 6750 motorists revealed one in three drivers admitted being a perpetrator of road rage over the past year.

One in 10 said they got out of their car to confront another road user and more than half of those indicated they did not regret it.