Chris Bishop turns down easing truck weight restrictions

The Transport Minister has told truckies he won't grant their wish to carry heavier loads, saying it will wreck roads and cost too much to fix.

Transporting New Zealand has long been calling for the government to ease truck weight restrictions.

The pressure has amped up during the fuel crisis, with the industry arguing the move would mean they took fewer trips and used less fuel.

But Chris Bishop on Friday told its conference that would not be happening.

"Not because we're opposed to change, but because the analysis didn't stack up," he said.

Officials modelled looser weight restrictions would deliver potential diesel savings of up to 16 million litres over six months, which amounted to about 1.5 days' diesel use, Bishop said.

"Achieving those fuel savings would have come at a cost of around $150 million in additional infrastructure damage over the same period.

"When it came down to it, the clear advice that we received is that the costs outweighed the benefits."

The measure was being kept "in reserve" and would only be relied upon if the situation worsened, he said.

Bishop pointed to a range of other changes in the country's fuel response plan that would come into effect if things worsened, like lifting route restrictions on bigger vehicles so they could use key Auckland motorways.

Bishop goes off script

Speech notes provided to media suggested Bishop intended to lay down a harder line.

"I want to be very clear about the Government's position: we are not in the business of subsidising the freight sector," the notes said.

However, Bishop softened the message in the room.

"I want to make clear, the government's position is: we want to make sure we get the policy right," he said.

"Any changes we make will need to ensure the effects on infrastructure are properly accounted for and managed through the system."

Bishop said work was underway on long-term reform including potential changes to vehicle weights and dimensions.

He stressed the long-term nature - rather than a sudden response to a crisis - was necessary to give the transport agency time to plan for road design and maintenance.

Bishop and Regulation Minister David Seymour also confirmed other previously announced fuel crisis response measures would take effect from 6 August.

They included allowing more drivers to drive heavier electric vehicles, and removing permit requirements for '50MAX' trucks which are higher capacity.