The so-called Latte Line. Mr Roberts who, with chief commissioner Lucy Turnbull, will be influential in drawing up the next metropolitan plan for the city, says the concept of the "line" demonstrates where the energies of city planners and developers must be focused. In essence, more jobs are being created to the north of Mr Roberts' line. But more housing is being created to the south. The result is congestion, unemployment and frustration. "The structural problem Sydney has … the fundamental, wicked problem … is the issue that our jobs are in the east, and our housing development is in the west," Mr Roberts told a breakfast this week hosted by the property developers' group Urban Taskforce. "Twenty years ago, most of our housing development was much closer to the eastern agglomeration. We are now talking about 60 to 70 per cent of housing supply coming on stream west of the M7… over the 40-year period," he said.

Geoff Roberts, economic commissioner at the Greater Sydney Commission. Credit:Greater Sydney Commission "So we've got a major cliff coming to us at some point of time in terms of congestion and housing affordability if we don't think about restructuring the city." Mr Roberts said the concept of the latte line could also be called "the goats cheese line". "It's a concept that says employment, education levels, social disadvantage, all the things that make a city less productive and less liveable than what we would all desire, you can pretty much draw a line from the airport through Parramatta, just to the west of Parramatta up to the north-west sector. "If we keep doing what we have been doing, that's only going to get worse in the next 10 to 20 years as more people live and work further away, or you get underemployment which obviously impacts on the overall productivity of this beautiful city."

To address the issue, the Greater Sydney Commission is investing a lot of expectation in the Badgerys Creek airport, to be opened in the middle of the next decade. The Greater Sydney Commission has dubbed the area around the airport Sydney's Western City, with Parramatta the Central City, and the existing central business district the Eastern City. Mr Roberts said the commission, which next year will finalise district plans intended to guide development across the city, was envisaging "defence and aerospace and advanced manufacturing" industries to be located near the new airport site. "We are quite well advanced, actually, already in our liaisons with global players to talk about what it would take to bring them to western Sydney," he said. Otherwise, health and education opportunities could also provide a new means of rebalancing the city's jobs.

Mr Roberts said Penrith, Blacktown, Campbelltown and Liverpool, for instance, could become "a string of university cities in the next five to 10 years". During the breakfast, Mr Roberts received critical questions from developers about the lack of detail in the draft district plans released last month by the Greater Sydney Commission. However, those draft documents already hold some weight - as they can be used by councils and other development consent agencies in deciding whether or not to approve a development. Next year, the commission will finalise the draft district plans, and also contribute to the creation of a new metropolitan plan and transport plan. Mr Roberts said the metropolitan and transport plans would be created together.