Wellington mayoral candidate Conor Hill has put his stake in the ground over the city's light rail versus trackless tram debate.
He wants to see light rail on a new mass rapid transit spine that's part of the $6.4b Let's Get Wellington Moving package.
Incumbent Justin Lester has previously said he's personally in favour of trackless trams.
Last week Transport Minister Phil Twyford said his personal preference was light rail.
But both said the decision would appropriately and transparently be made through a detailed business case.
Hill on the other hand wants to skip the business case stage and move straight to detailed design work for light rail.
That's because trackless trams were unproven technology and buses did not have the capacity, so both were a waste of time, he said.
"Light rail is the only proven technology that can deliver a reliable, carbon neutral transport system for Wellingtonians. We need to start building it as soon as possible.
"If you're wondering what a trackless tram is, you're not alone. They exist mainly in Justin Lester's imagination. By contrast, light rail is proven to work in hundreds of cities."
Lester said he was looking forward to investigating trackless tram technology on a planned trip to China, although that has now been pushed back until after this year's local body elections.
He supported a business case for mass rapid transit technology because it was such a significant project.
He also pointed out Let's Get Wellington Moving was a partnership between the city council, regional council and the Government.
"To make an executive decision without a business case would be reckless and naïve.
"I'll make sure we do a proper business case, I'll keep the options open. We'll determine which is best, light rail or trackless trams, based on independent advice, based on a sound business case and rational analysis", he said.
Hill proposed that if he was elected, light rail construction would start by the end of his first term.
But using Canberra as an example, Lester said building light rail would take about six years from start to finish, comprised of up to four years of analysis and consenting, and two years of actual construction.