A safety review has found 81 trucks and other heavy vehicles with problems that are high risk.
Photo: 123RF
Figures released by the Transport Agency under the Official Information Act show it has revoked the certifications of 33 of these, and of 43 vehicles in total.
In half these cases, the problem has been with towing components, most commonly with towbars.
"Our technical team have suggested a common cause for the non-compliance is calculation error, for example the component is over stressed and often does not meet the rule or design standard required," the agency said.
It has spent almost $6m - not counting consultants and contractors - since last year on the ongoing review, and inspections and recertifications resulting from it, as part of more than two years of investigations into heavy vehicle road-worthiness.
Last year, more than 3000 truck and heavy vehicle certifications were revoked, after belated audits identified poor work by two certifying engineers in Nelson and Auckland.
