One big bank's monthly economic indicator for the transport sector, the ANZ Truckometer, fell 1% in July.
The Truckometer uses traffic volume data published by the New Zealand Transport Agency to map quarterly GDP growth.
It suggests weak GDP growth in the second quarter, with some weakness persisting into the third quarter, before a rebound in the fourth quarter.
And it says that in the wake of recent falls, the signal for the first months of 2013 will be weaker, unless the Truckometer rebounds in the next two months.
