Unfortunately we forgot this meaning about three decades ago.

Transport infrastructure should drive the shape and operation of a city, just as it did in Sydney in the 1950s and 1960s. In those decades Sydney expanded along the railway lines and the arterial roads. These spines took travellers -- in trains, on buses, some in cars -- to the city or to regional centres or to industrial zones.

Three things resulted from this matching of urban growth and infrastructure roll-out, so people were able to structure their daily lives around some pretty basic assumptions. One was that they could get a train or a bus from the suburb where they lived to their place of work. Another was that they could walk to their local shopping centres and buy their weekly needs: fresh meat and vegs, fresh (sliced white) bread, newspapers, dry cleaning; as well as visit their doctor and dentist. And a third was that their kids would go to a good local school and get there safely by foot or bicycle.

From about the 1980s, these three things collapsed as we built new suburbs. The public transport infrastructure didn't grow and so urban growth wasn't steered along new public transport corridors.

New employment zones grew up willy nilly; and people took to their cars to get to work.

At the same time undercover shopping malls gutted the suburban shopping strips; and people took to their cars to go shopping.

Finally, parents decided it was a good idea to bypass their local schools for allegedly better schools somewhere else; and people took to their cars to drive their kids to school.

We now know the net result: Sydney's post-1970s suburbia is a daily rat race of car dependent commuters and travellers. In today's Western Sydney 80 per cent of full time workers are car-dependent. This is probably the highest car commuting rate for any major urban region in the developed world.

And so the NSW government is playing catch up, trying desperately to overlay public transport infrastructure over the top of the rats' maze rather then spending to steer new growth -- an option no longer open to it.

Last weekend's announcement by the state government of new heavy rail links to the north west and the south west, and of expanded capacity for the western line to the city, are exactly what Sydney needs. Oops -- I meant to say, exactly what Sydney needed, about three decades ago.

Phillip O'Neill is Professor and Director, Urban Research Centre, The University of Western SydneyPhillip O'Neill is Professor and Director, Urban Research Centre, The University of Western Sydney