Six hundred more trucks have been forced off the road in the safety alert over cracked and inadequate towing connections.
Photo: RNZ / Supplied
The New Zealand Transport Agency (NZTA) has revoked the certification of 616 draw beam and draw bars on big truck-trailers.
This follows the 802 tow bars revoked last week.
Road Transport Forum chief executive Ken Shirley said it was having "a huge impact and a shock" on the industry.
"They virtually have to take these vehicles off the road immediately," he said.
The west coast of the South Island was hardest hit, as it had no heavy vehicle certifiers to check the vehicles.
There are only two heavy vehicle engineers for Nelson, Marlborough and the West Coast. They have already faced months of backlogs.
NZTA said it could get all the trucks checked within a fortnight by bringing in more engineers, Mr Shirley said.
All the revoked towing connections were certified, and some designed, by Peter Wastney Engineering near Nelson. About 1500 were being looked at after the agency began investigating last August after a trailer broke free of a truck near Murchison.
The incident resulted in Peter Wastney's suspension as a heavy vehicle certifier.
Mr Shirley said the industry was disappointed the NZTA's auditing and accreditation processes did not pick up the problems with Mr Wastney's certifications earlier.
"The sheer number of vehicles affected shows a significant lack of regulatory oversight," he said.
"We want an assurance there are no more Wastney-type situations out there."
An industry player told RNZ that Mr Wastney "has consistently had poor reviews undertaken by the NZTA reviewer".
Mr Wastney did not respond to RNZ's calls.
RNZ is seeking comment from NZTA.
In a statement, it said it would cover re-certifications - a turnaround from last week when it claimed drivers would have to cover the cost.
"The real cost to an operator is the impact on the business," Mr Shirley said.
Dennis Cadogan operates a transport company on the West Coast was and was caught out by last month's and the most recent revocations. His trucks remain off the road.
The whole thing was a "bloody nuisance", he said.