Ms Hall died in March 2015 when she was riding her mobility scooter along Oxford St, the town's main thoroughfare and part of State Highway 1, and was struck by a transport agency vehicle driven by McGonigal.
He was driving out of the Horowhenua District Council building on a stretch of road that previously had a barrier in the middle.
But the barrier was removed before the crash and during his trial McGonigal said his team made the decision to get rid of it, Fairfax reported.
A sign at the carpark exit indicated people should turn left, but McGonigal turned right and struck the scooter.
In court, he said the sign was a leftover from when there was a barrier in place and he thought it was safe for him to turn.
Ms Hall's daughter supported McGonigal getting a discharge and permanent name suppression, but Judge Gregory Ross declined to keep the official's name secret.