THE condition of a man critically injured in a crash on the Hume Freeway has improved as detectives from the Major Collision Investigation Unit investigate the matter.
Graham Arkle, 54, was thrown from his ex-army amphibious vehicle at Glenrowan West on Wednesday night.
The vehicle had been struck from behind by a B-double driven by a 55-year-old man.
The driver stopped and was spoken to by police before being released pending further investigation.
Police are looking at whether a third truck was involved.
Officers had struggled to find the crashed 1964 Alvis Stalwart at the scene due to darkness.
Mr Arkle was found about 10 metres from his vehicle after yelling out for help.
He had been in a critical condition when transported to The Alfred Hospital in Melbourne by an air ambulance.
A spokeswoman for the hospital said his condition had improved to serious but stable by Friday.
The 54-year-old father been travelling to the Corowa Swim-In and Military Vehicle Gathering, where he has been a regular attendee.
He has used his unique vehicle to take people on trips in the Murray River.
Fellow attendee Jared Archibald said event goers were “hoping and praying that he pulls through”.
Mr Archibald had passed the collision scene on his way to the event and realised the crash involved Mr Arkle.
“A lot of people know him because of his vehicle,” he said.
“He’s well known because of the vehicle.
“We’re all just mortified that something like this has happened to him.
“Our thoughts are with him and his family.
“It’s just horrible.”
Mr Archibald said the incident was "in the back of everyone's minds" at the event, which has been a long-running fixture at Corowa.
Police said the incident was being examined.
"The exact cause of the collision is yet to be determined and the investigation is ongoing," Sergeant Megan Stefanec said.
"Investigators are appealing to the driver of a third truck that may have been involved in or witnessed the collision to come forward."