Last week a Herald editorial asked whether a heavy rail spur from Puhinui to the airport would be a better option for Auckland than the planned light rail network. It's a fair question, and one that the experts considered closely before deciding that light rail is the best option. Let me share the reasons for that with you.

We need proper public transport to the airport, and between the two fastest-growing job centres in Auckland — the Māngere business precinct and the CBD. We also need transport capacity to support the increasing populations of suburbs throughout the city.

In particular, our redevelopment of state house land will mean thousands more affordable KiwiBuild homes in Māngere and Mt Roskill. We need to enable our people to move from home to work, to school, and everywhere else they need to go, without ever worsening congestion.


Only a light rail network, including light rail from the airport and Māngere to the CBD, can achieve all these goals, according to the experts at Auckland Transport (AT) and independent transport economists.

Light rail can carry large numbers of people, rapidly, through existing roads. That enables growth and more medium-density housing. Each light rail line will have the capacity of a four-lane motorway without needing the huge amount of land a motorway requires.

So, when we say we're going to build two-way light rail routes from the city centre to Māngere, to West Auckland, to the North Shore, and, possibly, across South Auckland, we're talking about adding capacity on the scale of a new motorway network at a fraction of the price — all of it interconnected with the existing heavy rail and bus networks.

Light rail in dedicated lanes, separated from road traffic and synchronised traffic lights, is as fast as commuter rail.

What about heavy rail? A glance at a map tells you Puhinui is the closest existing rail station to the airport.

But, a heavy rail spur from the airport, connecting to the existing network at Puhinui, would be surprisingly expensive, costing at least $1.5 billion, and it wouldn't increase the overall transport network capacity. Instead, it would mean trying to send more trains into the CBD on the southern line, which is already near capacity.

A heavy rail spur also would not deliver any of the benefits light rail will bring to the communities it will run through. More than 90 per cent of forecast trips on the Māngere to CBD light rail line will be Aucklanders moving to jobs in the city or near the airport, or to schools and other activities. A heavy rail spur, on the other hand, is only really useful to airport users going to and from the CBD.

The experience overseas is that light or heavy rail lines that solely service airport travellers don't get enough passengers to justify their cost. To stack up economically, they have to also have to be useful to people moving around their city. But that doesn't mean we shouldn't look to connect Puhinui to the airport.


One of the first tasks I gave to NZTA was to work on rapid public transport from Puhinui station to the airport. It will be a bus service to begin with. In the future, it will become part of a rapid transit route connecting to Manukau and Botany with a dedicated busway or possibly light rail.

This will increase capacity and create growth opportunities along that corridor, which a heavy rail spur would not.

Light rail is a game-changer for Auckland. It is not just about connecting the airport to the CBD. It is about building a network, across the city, that can carry as many people as a motorway, while taking up far less land and using electricity, not fossil fuels.

The question isn't whether light rail is the answer. Nearly every expert agrees it is, including Auckland Transport, the New Zealand Transport Agency, Auckland Council, the Chamber of Commerce and the independent experts. The question is why we didn't start work years ago as other cities around the world did.

A world-class city needs a world-class, environmentally friendly transport network. My vision is for Auckland to be an even better place to live — a truly world-class city in the 21st century. To achieve that, the transport investments we make have to stack up, and the experts say light rail is the best value for money option for Auckland.

• Phil Twyford is the Minister for Housing and Urban Development and Minister of Transport.