As our new prime minister, Malcolm Turnbull, puts urban-planning centre-stage, for example by appointing our first Minister for Cities and the Built Environment, now is the perfect time to look at the direction other cities are taking.

New York has discovered the value of green space following the huge success of the High Line, which turned disused railway lines into parks.

Building on the public's love of urban parkland, architects Perkins Eastman are proposing turning New York's iconic Broadway into a diagonal 'green line' of parks across the city.

The plan allows emergency vehicles to maintain access to the park, and will create a bike lane that runs the length of the street.

The work builds on recent changes to New York's busy streets. Time Square is already closed to traffic, and there have been moves across Manhattan in recent years to improve bike access.

The design would also help to alleviate some of the pressure on New York's overloaded storm-water system, as the exposed soil would absorb more water than the existing concrete.

The success of the High Line has inspired other ambitious public space plans for New York.  Architecture firm, BIG, is developing plans to build parks and public spaces around the edge of Manhattan, in a plan called Big U. And a cross-shaped swimming pool that would float on the Hudson River is also on the drawing board.