Taree man Graham Squires is standing trial in Wollongong District Court this week on two charges of dangerous driving occasioning death over the June 28 incident, which claimed the lives of John Cerezo and Catherine Camilleri.

In his opening address to the jury on Monday, Crown prosecutor David Scully said Squires was travelling southbound in the exit-only left-hand lane when he merged into the middle lane near the Mt Keira underpass, allegedly cutting directly in front of a large blue Mack truck towing a trailer.

"On the Crown case, when [Squires] turned in front of the Mack truck, that caused the truck to come to an abrupt stop and pushed [Squires'] car sideways into a concrete barrier," Mr Scully said.

"[Squires' actions] caused a multi-vehicle collision behind that truck involving a number of cars and trucks."

Mr Scully said a white Mitsubishi Pajero containing Mr Cerezo and Ms Camilleri was travelling directly behind the Mack truck and careered into the back of its trailer.

The Pajero was in turn hit by an Isuzu truck, causing it to be crushed between the two larger vehicles and catch fire.

Mr Cerezo and Ms Camilleri perished in the ensuing blaze.

Mr Scully said the Crown case was that Squires was driving in a dangerous manner when he merged in front of the truck in such close proximity to the larger vehicle, and that his actions directly caused the subsequent crash that killed Mr Cerezo and Ms Camilleri.

Dashcam footage of Squires merging in front of the Mack truck was played in court on Monday, showing the truck's descent down Mt Ousley, then the moment Squires' silver Ford Territory merges in front of the truck.

The footage clearly shows the truck subsequently hitting the Territory and being pushed into the concrete barrier.

Meanwhile, defence barrister Luke Brasch said Squires denied his driving that day was dangerous

"The defence case is he was driving within the speed limit, with due care, and did what the road required him to do, which was merge [into the middle lane]," he said in his opening address to jurors.

"He increased his speed and pulled beyond the truck, he looked and indicated to move into lane two."

Mr Brasch said it was the defence case that the driver of the Mack truck closed the gap Squires had created between his car and the truck and that he "must have seen Squires' vehicle as it moved into the lane".

"Mr Squires may have made a misjudgement or a mistake but [his manner of driving] does not rise to the level of dangerous," he said.

The trial will continue before Judge Stephen Norrish on Tuesday.