The Transport Agency says heavy rail to the airport was rejected because it doesn't provide "sound value for money".

The agency said it was focused on investigating and investing in the most appropriate transport option between Auckland city and the airport.

The NZTA's Auckland regional director, Ernst Zollner, said this was proved through its commitment to fund a 51 per cent share of the costs to provide a trench through the Kirkbride intersection as part of the State Highway 20A project, which will be wide enough to enable any future rapid transit solution.

The East West Connection is also enabling for a rapid transit connection to the Airport. Stage 1 of the project involves removing the Neilson Street rail bridge and creating a new, lowered road.


"Eventually any rapid transit system will be elevated and go over this road," Mr Zollner said.

However, critics have said removing this bridge increased the cost of heavy rail to the airport as it would have to be rebuilt.

Mr Zollner said the advice from Auckland Transport comparing various rapid transit modes signaled a heavy rail line along SH20A did not provide sound value for money. A heavy rail option would also require tunnelling and an underground station to serve the airport terminal.

"There's an enormous amount of work to do to resolve Auckland's transport challenges and the priority and timing/staging of options for a rapid transit network will be considered as part of the Auckland Transport Alignment Project."