In cities experiencing rapid growth, a tried and tested response to meeting itis through the planned establishment of new cities, geographically close to, but separate from, the main metropolis.

Take Springfield, 50km south of Brisbane's CBD. In the early 1990s a visionary developer bought 3000ha of raw land and worked with authorities over two decades to unlock it. New rail and motorway investment, combined with new homes priced well under $420,000, has made Springfield Australia's fastest-growing city. In 20 years, its population is projected to more than triple and there will be 50,000 jobs. That's 50,000 trips which aren't converging on Brisbane's CBD. Where is Auckland's Springfield?

Sydney recognised a good idea and is taking it to the next level. The new Western Sydney vision is for a city with 200,000 jobs — that's twice the size of Auckland's CBD. The catalyst will be a new airport, which authorities are going to augment with a new aerospace institute and 11 new schools.

This co-ordinated and aligned plan for a new community and industry will be delivered by a development authority, supported by the federal and state governments.

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What's Auckland's plan to leverage its investments to inspire and support new growth and development? Fast-growing Denver, Colorado, was confronted 30 years ago with a big infrastructure decision: renew the existing airport or build a new one. Renewing would be cheaper, but would that deliver the best result for Denver?

A brand new multi-runway airport was constructed to reposition Denver as a transport hub, while the 1000ha old airport site 20km from Denver CB was redeveloped into housing and employment. Some 26,000 residents now call the old airport home and the whole project has created an incredible $4.8 billion of new value.

Authorities saw the opportunity and they took it. What would Auckland have done? Woodlands, Houston is a vast 12,000ha city of 116,000 residents and 66,000 jobs nearly 100km from downtown Houston. Built amid a forest, the developers have imposed strict rules around the management of trees.

The result is a city the size of Tauranga with the look and feel of Titirangi.

The development has been so successful, major multinationals have relocated to the city centre and house prices have increased rapidly. Thanks, however, to supporting development, affordable housing is now provided in adjoining suburbs, providing homes for just $295,000, 10 minutes from employment. Where is Auckland's vision for new communities?

An outcome all will benefit from

Last month, Auckland's residential building consents for the past 12 months hit 13,000.

That is great news — it means for the first time in a decade as many homes were consented as are needed to meet population growth.

But the region only built 9000 homes in the past year and almost none of these were affordable for the half of Auckland households who earn under $100,000. The underdelivery of homes to meet population growth has now left Auckland short of almost 50,000 dwellings. The scale and price of housing is not the only problem.

Almost three quarters of homes consented in the last year were houses on small sections, units or apartments, nowhere near the rapid transit network. This kind of suburban intensification without public transport access intensifies car dependence and makes traffic congestion worse, not better.

Meanwhile, most of the new transport spending is being directed towards a small number of rapid transit corridors linking to the CBD where less than 15 per cent of people work.

The resulting congestion makes Auckland the most congested city for its size in the developed world, while land prices in areas close to public transport are getting more and more expensive.

The region desperately needs an additional 4000+ homes completed per annum at prices people can afford and in locations where the transport system can accommodate them.

The whole country is dependent on Auckland resolving this issue. The city is simply too big to fail. Yet evidence consistently shows current plans won't solve Auckland's congestion and housing affordability crisis. A much more innovative approach is required.

The city needs homes priced at under $400,000 — four times the median household income. Since sections alone within the Rural Urban Boundary already exceed that price, greenfield land will need to be opened up. That land requires access to transport — rapid transit and roads — and existing and future employment opportunities to enable residents to live and work locally.

The only part of the region with the transport connections, commercial development potential and land supply necessary to support major development at scale is Auckland's south, from Drury to Karaka.

If SH20 can be linked from Karaka to Weymouth, the south has two motorways and a third key corridor in Mill Road that can be designed to improve road and public transport access.

The south also has rail. Light rail to the airport is on its way and can easily be extended to Karaka. Though not electrified beyond the urban fringe, heavy rail is earmarked for a third and fourth main trunk line.

Add in the greater ease of supplying water and electricity from the south, proximity to the airport and key employment zones along the southern rail corridor as well as connection to the Waikato and Bay of Plenty growth regions, and the south emerges as the only realistic option to meet Auckland's growth challenge.

And meet it, it can. There is 20,000 hectares of developable land in the south before you get anywhere near Auckland's productive soils around Pukekohe — that's more than the entire Auckland isthmus. It's difficult to overstate the opportunity here.

Rural land in Auckland's south costs between $10,000 and $20,000 a section. As soon as it is zoned for development under New Zealand's clunky and inequitable planning processes its value increases tenfold.

That additional $100,000-200,000 per section is what should be paying for infrastructure. Instead, it is captured by land bankers who have no interest in developing land but understand how to use the system for windfall gain.

The first job of the new Housing and Urban Development Authority (HUDA) should be sitting down with landowners around the rail line from Drury to Paerata to discuss development at pace.

Most of the landowners down there are ready to go, it's just red tape and council infrastructure provision holding them back — both of which can be fixed by the new Authority. With HUDA enabling development, rather than land inflation, we can turn up the dial on producing houses at pace.

An industry of standardised, prefabricated and pre-consented homes which take days to put up, not months, and which cost half per m2 to build can be established. This is how we deliver homes Aucklanders can afford — $300,000-400,000. That's half the prize.

By building at pace and scale along rail in a greenfield environment, we can master-plan, design and deliver a sustainable city of the future deploying the latest in technology and urban design.

Streets for electric cars, autonomous shared vehicles, active transport and even scooters.

The city can go further. All new homes should be delivered with solar energy, battery storage and garages equipped with electric vehicle rechargers. Grey water can be recycled, streams cleaned up and protected. The southern coast of the Manukau harbour should be the next Mission Bay.

Development at this scale and desirability will attract businesses and employment. A bridge across to Weymouth will put the south 20 minutes from the airport, catalysing major commercial development. More jobs mean less travel to Auckland's congested urban core. That's an outcome all Aucklanders will benefit from.

Stephen Selwood is chief executive of Infrastructure NewZealand.