Sustainability in the City

Sustainable Sydney 2030 gives us a peek at how the City of Sydney will develop over the next 22 years.
Green Transformers are mentioned quite a bit, and in today's Age the promoters of these transformers write a bit more about them in Sustainability must start in cities.
I confess I know nothing about transformers, but I really can't see how a transformer burning natural gas or biomass to produce carbon dioxide is of any benefit over the current transformers. I suspect the key is really in using the current waste heat to do some useful work, and I'm surprised that large city transformers don't do that already.

I digress however.
Back to the point: 'sustainable cities'.

Roads already exist. The bitumen used to make roads comes from the petroleum industry. As petroleum (read oil) prices increase, the cost of building and repairing roads will also increase. So, one of the keys to making cities more sustainable should be to encourage forms of transport that do the least road damage, and have the lowest impact on the environment. Building motorised vehicles that reduce environmental impact will not reduce road damage, but encouraging active forms of transport (read cycling, walking, skateboarding etc) will.

Encouraging people to physically exert themselves is hard. So, don't try to encourage them. Prevent them from using damaging forms of transport! Which brings me to New York city, Where the Streets Have No Cars. New York has roughly the same population as Australia. It has a dedicated car culture. And yet, they are prepared to temporarily close off some roads to motorised traffic,

On three August Saturdays this summer, New Yorkers will be able to ride their bikes all the way from the Brooklyn Bridge to Central Park – a 6.9-mile route - without a single cabbie honking at them or absent-minded driver smashing them into a parked car. This rare opportunity comes courtesy of the newly-launched "Summer Streets" program. For six hours, a major route running north and south along the island of Manhattan will be closed to traffic and opened up to walkers, cyclists, even outdoor yoga classes hosted by the gym chain Crunch Fitness.

The only times we close off streets in Sydney is if someone plays enough money, eg, filming movies and commercials, or if a foreign nation (or our own government) demands it for "security" reasons.

Why can't we, a very small city in comparison to New York, manage a similar program of temporary road closures to entice people to enjoy our city?
Why can't we, even temporarily, replace the never-ending noise of traffic with the sounds of happy people enjoying themselves?
Why can't we, even for a short time, enjoy a breath of fresh air in an otherwise dirty, smelly, city?