Auckland super-city mayoral candidate Andrew Williams wants four road and rail tunnels under the Waitemata Harbour completed in 12 years.
In a policy statement released on Sunday, Mr Williams says the tunnels to the North Shore should be funded by the private sector.
A study of harbour crossing options two years ago priced the idea at up to $5 billion.
Mr Williams, the North Shore City mayor, is also promising a $2 flat fare for students on public transport, aimed at getting more commuters out of cars.
He would like a section of Quay Street in Auckland's CBD to be put underground so a pedestrian zone can be created, linking the downtown area to the waterfront.
Mr Williams is pledging economic growth targets will be set for the Auckland region.
