"I was like 'whoa, what's going on here?' At first I thought he might just be, like, drunk or just mad at life and trying to get around the traffic.
"I kind of watched him just cruising along that inside lane."
Traffic was bumper to bumper and moving about 10-20km/h, or "a fast walk", Jones said.
"I pulled up next to him and looked across. He just wasn't there, I could tell something was going on.
"No one was pulling over. People were slowing down and looking at him and just driving off."
Jones leaped into action, pulling his car over and running over to the other man's car - which was still moving - to stop the vehicle.
"I just boosted ... I ripped his door open and slammed the handbrake up.
"It became clear to me that he was having a seizure."
Jones stayed with the man and "kept him calm" until paramedics arrived on the scene.
"He didn't know what the hell was going on."
Jones said the man explained he started to get a headache and pulled over onto the shoulder before the seizure began. He had never had a seizure before.
Jones didn't know what would have happened and said it was lucky no other cars were hit. The vehicle travelled about 500m after hitting the works end sign.
"At the time I didn't really think too much of it ... it hits home because my brother has seizures and stuff. All I was thinking was like bro, that could have been my brother. I would have hoped someone would have done the same for him."