A move to extend the weight carrying capacity of heavy trucks won't lower the road toll but will compromise the viability of rail and shipping, the Green Party says.
The claims come as a transport rule change, set to take effect on May 1, allows for trucks with the required permits to boost their loads from 44 tonnes to 53 tonnes on specified routes.
Transport Minister Steven Joyce said the Land Transport Rule: Vehicle Dimensions and Mass Amendment 2010 allowed the development of a permit regime for 'high productivity vehicles" to increase their capacity, and there would also be provision to allow for loads above 53 tonnes under specific circumstances.
It would not mean trucks would be wider or higher, but some would be longer.
Mr Joyce said New Zealand's freight task was forecast to increase by 70 to 75 percent over the next 25 years. Rail and coastal shipping would play an increasingly important role in meeting that task, but the bulk of the increase was expected to be carried on roads.
Green Party spokesman Gareth Hughes said the involvement of trucks in road deaths was high and way out of proportion with other vehicles, and increasing the number of heavier trucks would add to the danger.
The increased weight would also be damaging to New Zealand's roading network and leave extra expenses to ratepayers which would not be covered by increased road user charges.
"Neither will they cover the upgrading of hundreds of bridges in our road network to accommodate the increased loads," Mr Hughes said.
He said KiwiRail had estimated it would lose 12 percent of its freight tonnes because of the move to heavier trucks, yet there didn't appear to be any analysis from the Government on how the safer and more sustainable forms of freight transport, such as rail and shipping, would be affected.
Mr Joyce said productivity gains of between 10 and 20 percent could be achieved by using fewer trucks to carry a given amount of freight.
