Safety alert after wheels hurtle off school mobile dental clinics

A safety alert has gone out about wheels flying off school mobile dental clinics.

By Phil Pennington for rnz.co.nz

Twice a wheel has sheared off the heavy trailers and gone flying across the road.

The alert went out yesterday, although the first time a wheel flew off was at 90km/h on a highway near Cromwell in 2017, and the second on Tauranga’s main Cameron Rd in 2020.

In that case, the wheel flew over a car and smashed into a building. No one was hurt in either case.

RNZ sent the alert separately from Health New Zealand, which put it out internally three days ago.

“This situation is clearly unacceptable,” a spokesperson told RNZ on Thursday.

Health NZ is telling health districts to check all 23 trailers across the country and to consider taking some off the road entirely to check their wheel assemblies.

The large caravans sit on double five-tonne axles.

A photo from the Cromwell scene showed all the wheel studs had been completely shorn off – the wheel flew over the road and into Lake Dunstan.

A certifying engineer who checked the wheel wrote, “Wheel studs on stud-centred set-ups are prone to failure from loose wheel nuts.

“They are subject to cyclic stress from every wheel revolution and fail from fatigue quickly.”

Health NZ has not said when it was made aware of the wheels flying off.

“Inquires and subsequent incident investigations concluded that the incorrect wheel assembly was attached to the hub resulting in the shearing [sic] of the wheel studs while being towed,” its alert said.

Anyone towing the clinics should be “vigilant”, was among its advice.

After the Tauranga case, the operator in charge of the move who saw the aftermath, raised the alarm with NZTA, over 18 months ago.

Since then the operator, fearing another failure, only moves the clinics by putting the whole trailer up onto a separate truck.

RNZ has approached NZTA for comment.

The manufacturer of the two trailers, who RNZ is not naming at this stage, said last night they “absolutely” stood by their trailers.

The trailers had been cleared in two investigations already, but a third investigation had begun, they said.

They were not aware of the Health NZ safety alert until RNZ contacted them, they said.

The clinic vans are about nine years old. They are moved regularly between schools but do not do many kilometers.

Health NZ said it expected all districts to make sure “appropriate actions are taken” and that it would follow up with them.

“Our advisory demonstrates a number of actions already taken, including remedial actions already carried out by districts, and notifications to police and NZTA.”