The rail workers' union says the asbestos problem that's led to 40 Chinese made locomotives being taken out of service is costing KiwiRail $3 million to $4 million a week.
Asbestos is being removed from all the doors after it was discovered there was a risk of it escaping, and a second round of tests began on Saturday to establish if there was a chance of exposure after heat was applied to the highly toxic material.
The Road Transport Forum has already reported suppliers having to stockpile produce at the farm gate because of the shortage of locomotives.
KiwiRail says it will be suspending shipments of logs from three Northland suppliers from Monday as it diverts trains to higher priority areas.
The Chinese locomotives have now been parked up for nine days since Friday 28 February and while the state-owned enterprise has said it hopes to have some of them back on the tracks within a week, it's still not able to definitively say when they will be back in service.
General secretary of the Rail and Maritime Transport Union Wayne Butson says the $3 million to $4 million the situation is costing KiwiRail each week doesn't include the cost to the wider economy.
"Remember this is going to put freight delays onto customers, onto manufacturing, it also means trucks are going to be doing many more vehicle kilometres and therefore the fuel usage of the country will go up.
"New Zealand Inc. is paying a cost for this."
Kiwirail says it's too soon to put a figure on how much the problem has cost its business, but it hopes testing work this weekend will help get some engines back on the rails within a week.
Tests have so far been done on on 33 of the 40 locomotives and the remaining seven still need complete checking.