The pieces of Auckland's motorway puzzle are falling into place - and the biggest piece, a second harbour crossing, is looming large in the minds of planners.

Yesterday the $220 million Hobsonville motorway opened to the public, a milestone in plans to ease pressure on Auckland's State Highway 1.

In the next five years a tunnel through Waterview will complete the Western ring route, giving motorists an alternative option to travel from Manukau to Albany.

And the mother of all roading projects, a replacement for the Auckland Harbour Bridge, is edging closer, according to New Zealand Transport Authority Auckland state highways manager Tommy Parker.


'The next step up in size and scale will be another harbour crossing," he said.

For now though, he and other officials are patting themselves on the back for some speedy work.

The public were allowed to walk on the new 6km, four-lane motorway yesterday before it opened, connecting the northwestern motorway at Hobsonville Road to Upper Harbour Bridge. The project also includes a 3km, four-lane extension of the northwestern motorway north to Whenuapai.

Parker said Auckland's motorway system was now "just a few pieces short of the puzzle".

"It's a move away from the single access of State Highway 1 and will give us a robust resource now that connects with the economically productive areas of Auckland.

In the past 10 years the Spaghetti Junction upgrade, the SH20 extension at Manukau and the addition of an extra lane on the Newmarket Viaduct have all been completed. The completion of the Victoria Park tunnel was next.

Transport Minister Steven Joyce said travellers would see a significant improvement in travel times from 2015 onwards.