Another tunnel pitched for Wellington as population tipped to increase 30 per cent in a decade

Karori residents have proposed a second tunnel as their population increases. Photo / Supplied

Karori residents want a second tunnel in and out of their suburb at its population expands.

Retired civil engineer and local Bill Guest has been enlisted by the Karori Residents' Association to design the proposal, a tunnel which would stretch 350 metres between Chaytor St and The Rigi.

A separate safer tunnel would also be built for pedestrians and cyclists with access to Kelburn and Victoria Universities.

The cost of the tunnels could be covered by central government, targeted rates and possibly tolls, he said.

With the population of the Wellington City Council area set to increase by 30 to 40 per cent by 2030, Guest said the new tunnel is desperately needed.

"Right now, both the suburb's residents and wider catchments of Makara, Creswick Valley, Northland, Wilton and Otari are captive to a now hopelessly inadequate tunnel that effectively throttles residential and commercial transport of all types, particularly at peak hour."

The state of the existing tunnel, which cannot be upgraded or enlarged, is affecting 25,000 people in Wellington's western suburbs, he said.

"It directly stifles public transport such as double-decker buses and is dangerous to ordinary buses, commercial trucks and vans, cycle traffic, pedestrian traffic and private vehicles. The tunnel in its current form is well past its 'best-by' date."

With a proposal already on the table for a second Mount Victoria, residents hope a second tunnel in Karori could be part of the wider Let's Get Wellington Moving transport project.