The Southland-based trainer-driver was dislodged from the sulky just as Captains Mistress looked set to win the group 1 Queen Of Hearts.
The 37-year-old was taken to Auckland City Hospital with serious head injuries, and temporarily placed in an induced coma.
His progress is "remarkable", according to father Phil Williamson, who provided an update on The Box Seat.
Williamson has a fractured skull and other broken bones but has been communicating well with friends and family and there have been other positive signs as well.
"He got out of bed for the first time today [Tuesday]walking to the toilet with assistance," Phil said.
"He had nurses on either side and that’s massive progress from where we were."
So far there’s been no indication of just how long he will remain in hospital.
"Rest is now the key thing."
The family has also been very grateful for the huge outpouring of support since Friday.
Meanwhile, Harness Racing New Zealand has responded with a package of sulky safety measures following the fall
"The wellbeing of drivers, horses, and all participants remains paramount," HRNZ head of racing and wagering Matthew Peden said.
"HRNZ recognises that the incident has prompted important questions and discussion across the industry.
"We consider it appropriate to outline the steps currently being taken to review and strengthen sulky safety practices."
HRNZ is working closely with the Racing Integrity Board and the New Zealand Harness Trainer Driver Association to review several existing practices relating to sulky safety and compliance.
Particular attention will be paid to checking the integrity of welded joints.
In conjunction with sulky inspectors, HRNZ will provide free sulky inspections to any owner who wishes to have their sulky checked in the immediate future.
While these inspections are not compulsory, HRNZ strongly encourages sulky owners to take advantage of this opportunity. — HRNZ
