Protection of views of Mt Eden for commuters coming across the Auckland Harbour bridge is limiting development at a cost of $1.4b, an economist says.

PwC economist Geoff Cooper has studied Auckland's viewshafts - which are planning tools aimed at protecting people's views of the isthmus' volcanic cones.

They limit the development of buildings in order to give visitors and residents alike unimpeded sight of Auckland's peaks.

The study, A City With a Billion Dollar view, focuses on the viewshaft protecting the vista of Mt Eden enjoyed by commuters travelling south across the Harbour Bridge.

This particular viewshaft was found to limit the development of approximately 1.7
million square metres of land.

Cooper put the conservative net cost of this at $1.4 billion, which he said was equivalent to 16 per cent of private land value in the centre of Auckland.

This raised cost for "homeowners, renters and businesses", he said.

"According to the research, each car crossing the Harbour Bridge would need to pay $14,498 to offset the cost," he said.

Cooper suggested the policy around viewshafts could be optimised to "provide a middle path for city planners that reduce the cost while preserving views".

"Viewshafts play a vital role in preserving our iconic views, but we need to have an honest
conversation about them and the trade-offs when it comes to affordable housing and employment opportunities for future Aucklanders," Cooper said.

"Until now, there has been minimal understanding of the economic impact of viewshaft policy and very little consideration given to their cost. This research changes that.

"Planning policies which constrain New Zealand's most productive employment area should carry national significance and be subject to robust scrutiny. If Auckland's CBD is to be internationally competitive and provide affordable options for homeownership and renters, new infrastructure is not enough – the city needs room to grow."

Volcanic Cones Society chairman John Street, in 2016, rallied against suggestions viewshafts could be scrapped. He said at the time that no viewshafts should be removed and more should be added.