The Green Party says falling traffic volumes prove the Government's roads of national significance are not needed.
A Transport Agency report shows highway traffic dropped by more than 1% in 2011, compared to the previous year.
The latest monthly average daily traffic report, for February, also shows a decrease of more than 3% compared to a year earlier.
Green Party transport spokesperson Julie Anne Genter says highway traffic has now dropped in five consecutive years.
She says that makes the case for more roads that much weaker.
Ms Genter says people's travel patterns have changed and the Government should be spending more in areas like public transport, walking and cycling - as that is where the growth is.
She says spending $14 billion on seven new roads is like throwing all your money into a technology that is about to be superseded by a new one.
Transport Minister Gerry Brownlee has been unavailable to comment.