The Road Transport Forum says the sidelining of 40 KiwiRail locomotives because of an asbestos problem will affect nearly every part of the New Zealand economy.
Asbestos is being removed from all the doors of the engines, after it was discovered there was a risk of the hazardous mineral escaping.
KiwiRail says it will be suspending shipments of logs from three Northland suppliers from Monday as it diverts trains to higher-priority areas.
The locomotives have now been parked up since Friday 28 February and while the company has said it hopes to have some of them back on the tracks within a week, there's no definitive answer on when they will be back in service.
The Road Transport Forum, which represents road-freight carriers, says every part of the economy needs goods to be transported, and the sidelining of the locomotives is a serious blow.
The rail workers' union meanwhile says the disruption being caused to KiwiRail's customers is the price to be paid for importing second-rate equipment from China.
It says the asbestos problem that's led the locomotives being taken out of service is costing KiwiRail $3 million to $4 million a week.
The general secretary of the Rail and Maritime Transport Union, Wayne Butson, says the disruption could have been avoided by having the trains built at Dunedin's now defunct Hillside Workshops.
Mr Butson says the problems all stem from a government procurement policy aimed at buying equipment at the cheapest possible price.
He says while none of the tests carried out so far have shown traces of asbestos that could harm workers, it is still not clear whether the mineral will stay contained when heat is applied.