Treasury papers have revealed that Auckland Government's plans for light rail in Auckland could cost up to NZD 29.2 billion, which does not include the cost of building infrastructure to realise the additional urban development planned along the route from the central city to the airport. The Treasury papers said information provided to it by the Light Rail Establishment Unit noted cost estimates with an accuracy range of -50 per cent to 100 per cent based on a very low level of design.In late January, Finance Minister Grant Robertson and Transport Minister Michael Wood unveiled the Government's preferred option for light running a hybrid system running in tunnels from Wynyard Quarter to Mt Roskill and then proceeding at street level to the airport. The ministers said the "hybrid" system had been chosen over two other options: light rail at street level costing NZDD 9 billion and light metro above or below ground costing $16.3b. This was because it had greater carrying capacity, was less disruptive and better aligned to a linked-up rapid transit transport network. The ministers said the new line would be designed, consented and built by the early 2030s at a cost of NZD 14.6 billion.The light rail project will connect the largest business and residential area in the country – the inner city – with the second largest employment area – the airport precinct. It will run past Eden Park and through suburbs that are expected to get 66,000 new homes with 150,000 more people living in them.