The Greens believe taxpayers will have contributed to the construction of Wellington's Transmission Gully two or three times over, once it's finally up and running.
The Government's announced it plans to construct the much-anticipated roading project under a Public Private Partnership - and it'll also be a toll road to help fund it.
Green MP Julie Ann Genter says the PPP is needed alongside the toll, because if the toll is too high, people won't use it.
"They know from their own figures that tolls will never pay for Transmission Gully, there just won't be the demand to use that road.
"There's been virtually no increase in traffic volumes on the route for over a decade."