But as she begins to walk, the massive machine begins to turn left into her path and hits her.
The driver stops for about 12 seconds but then leaves the scene.
A man, 58, later went to a police station for questioning.
Stevenson's brother Adam told TVNZ that she had started responding by squeezing her mother's hand.
He hoped she would make a 100 per cent recovery, but "it's never going to be same after getting hit like that".
"We'll just have to wait and see, and hopefully get some good news," he said.
"She's pretty outgoing, fun-loving, if she's going out for a drink everyone would want to go."
The vehicle involved in the incident belonged to Queensland Rail.
Chief executive Nick Easy called what happened "a tragic accident".
"Queensland Rail is doing everything possible to assist emergency services with their inquiries," he said.