After a sluggish start to the year, ANZ's Truckometer is pointing to a period of above-trend growth over the second half of 2013.
The heavy traffic index, which tracks flows of heavier vehicles on 11 roads chosen for a close historical fit to economic activity at the time, climbed 4.7 per cent last month on top of a 3.8 per cent rise in April.
"The index tends to seesaw, so to have two strong increases in a row is quite notable," said ANZ economist Sharon Zollner, who designed the index.
Taking the heavy traffic index more literally than Zollner would recommend indicates the March quarter was weak but the June quarter is very strong.