"He's tried to get out of the truck a little too late and as he was doing so the train has struck the truck and thrown him to the ground."
Mr Fitzpatrick did not believe the trailer was too low to the ground and said the two railway tracks were at the top of a rise in the road.
He said Mr Clements would have had less than 22 seconds from the first possible sight of the train to impact, to get the 18-metre Kenworth truck and trailer unit safely across the track.
Train driver William Henare said he sounded the horn of the 190-tonne train, which was carrying 108 passengers, to warn the driver to stop at the crossing, which did not have lights or barrier arms.
He watched with concern as the truck moved onto the track and stopped, with the cab straddling the southbound track the train was on.
"I remember thinking to myself 'this is not going to be good' because by then I'd seen what it was, I'd appreciated the size of it. This was not going to be good for everybody."
Mr Henare, who has 40 years experience driving trains and has hit a bike, car, truck and three pedestrians in that career, blasted the horn again but the truck did not move and he braced for impact, fearing for the lives of the passengers.
The inquest, attended by Mr Clements' wife, mother and sister, continues.