The economy may be hitting a pothole in the June quarter, according to the ANZ Bank's "Truckometer" – a measure of traffic around the country.
But there could be "glimmers of light" at the end of the tunnel, ANZ said.
ANZ's Truckometer is a new economic indicator, using traffic volumes as an indicator of economic activity because a large proportion of freight is moved by road. The new series shows a strong relationship with economic growth, with a lead of six months, according to ANZ.
The Truckometer rose 1.2 per cent in April, after falling 0.8 per cent in March.
The indicator fell sharply between October and December last year, steadied this year, but had not started to rise meaningfully yet, ANZ said.
"The Truckometer flags a bumpy road ahead for the economy," ANZ said.
Given the six-month lead to GDP, that suggested weak growth in the first half of the year, persisting into the September quarter, but steadying by the end of the year.
"With its unique six-month lead, the Truckometer is detecting glimmers of light that could signal the end of a tunnel that standard economic indicators are only just starting to reveal we are in," ANZ said.
The unwinding of the Rugby World Cup boost last year would likely dampen activity in the March quarter and if the Truckometer was right, the June quarter would be the weakest.
The broad message from the Truckometer was that activity would be "pretty mediocre" in coming months.
The heavy traffic indicator for large trucks was heading "mildly downwards and becoming increasingly consistent with a fall in GDP".
But ANZ said the path for the economy was "clouded in uncertainty", with the recovery from the 2008-09 recession tepid and stuttering, after a debt-fuelled party before the global financial crisis hit.