A judge-alone trial began before Judge Brian Callaghan this morning. It's expected to last three days.
The prosecution says that at about 3.15pm on December 9, 2017, the businessman was driving a large 4WD vehicle which was towing tandem axel cage trailer east on Tram Rd and approaching the State Highway One overbridge.
Caldicott-Elwell was riding a motorbike west on Tram Rd – on a section of road that had a 100km/h speed limit.
The businessman slowed to turn right from Tram Rd onto the motorway onramp which leads to State Highway One south to Christchurch.
The prosecution says that while turning right, he realised a motorbike was approaching but could not slow down in time, and tried to accelerate across the road.
But Caldicott-Elwell, who police would later estimate was travelling at 93km/h, hit the front left corner of the trailer.
Dr Ed Newman, a consultant orthopaedic surgeon was driving into Christchurch with his wife for a Christmas party when he came across the crash scene.
He tended to Caldicott-Elwell lying on the ground with blood coming from his head and said it was obvious he had suffered a major head injury.
Paramedics soon arrived and took over but he later passed away at Christchurch Hospital.
A post-mortem found he died from multiple head injuries, along with pelvis injuries and blunt trauma to his chest.
The prosecution says the businessman's driving was careless.
But defence counsel Andrew McCormick says that while the police say his client first saw the motorbike as he was initiating his turn, he had actually seen him earlier at the eastern end of Tram Rd.
McCormick says that will be a "crucial piece of evidence" during the trial.
The businessman's wife was in the passenger's seat and told the court she got a "fright" at the speed the motorbike was travelling and screamed "S***!", bracing herself in the seat.
"It's not what you normally see on the road," she said.
She says the motorbike was travelling "extremely fast" and appeared to be accelerating, with the rider "bent right down" over the handlebars.
Her husband accelerated, she said, but then heard a "bang … and a bit of a thud". They stopped and her husband went over to the bike rider, saw it was "bad", and called an ambulance.
A forensic toxicologist analysed a blood sample taken from Caldicott-Elwell which detected THC, the main psychoactive compound in cannabis.
The court heard that Caldicott-Elwell – who suffered a serious head injury in 2002 for which he took an anticonvulsant drug - was a recreational user.
His wife Samantha Caldicott-Elwell said he strictly took cannabis for personal medical use on a daily basis.
Forensic analysis of the THC was unable to conclude how much had been used, when it was last taken, or what effect it might've had.
Samantha Caldicott-Elwell told the court they'd been at a family outing to a Shirley mall and had been travelling home – with Ben on his motorbike, and her driving behind with their son – when the accident happened.
She had gone through Kaiapoi home to Rangiora while her bike-loving husband took a left turn onto Tram Rd to take advantage of riding a longer route home.
They had planned on meeting up at a Rangiora supermarket – but he never showed up.
Police later knocked on the door of their family home to say he'd been in a serious accident.
Workmates at The Plough Hotel in Rangiora described Caldicott-Elwell as a "kind soul" who "always meant well".
"Superheroes should never die so we're sure he will be riding his bike around in Superhero heaven," his colleagues said after his death.
The trial continues.
