By contrast, walkable urban development includes: higher densities, mixed-use real-estate products, and multiple transportation options, such as bus, rail, bicycle, and pedestrian-friendly footpaths, as well as motor vehicles, that connect to the greater metro area. Urbanists everywhere will be unsurprised that this form of development (and location) is the hottest in the market but delighted that someone has done some serious and big research to prove the point.

He thinks that we are seeing a paradigm shift in the market that may be reversing the previously dominant trend towards what he calls "drivable suburban approach dominated real estate development". This is characterised by low densities, segregated but standardised real estate product types and have cars as the predominant transportation mode. In other words, sprawl.

Leinberger says that such places in all 30 of the largest US metro areas he has reviewed are for the first time in 60 years "gaining market share over their drivable suburban competition – and showing substantially higher rental premiums". The premium for walkable urban office is 90 per cent, retail 71 per cent, and for rented apartment blocks 66 per cent over drivable suburban products.

By contrast, the "compact city" part of Sydney – within 10 kilometres of the CBD – is well served by mass transit, has a higher density, provides ample opportunities for walking and has a healthier population. That population is also wealthier and has a much higher proportion of graduates. I learnt from the excellent research of Christopher Leinberger and an outfit called SmartGrowth America that these outcomes are all linked and there is an increasing market premium for walkable urban places or "Walk-ups".

So far so good. What about the dimension of the "density" and walkable cities discussion which few mention but which matters a great deal to the inclusivity of our cities. That is what you might call inequitable access to the benefits of density. This is the western Sydney dilemma on the one hand and the problem of gentrification on the other. The less well-off can be disadvantaged by where they live now – increasingly in the sprawl city – or through being displaced from the compact city by higher costs. Leinberger has some positive findings to add to this crucial issue. He finds that while cities with the highest levels of walkable urbanism are also the most educated and wealthy they are also "surprisingly, the most socially equitable".

Leinberger says the reason for this is that overall the low cost of transportation costs and better access to employment in Walk-ups "offset the higher costs of housing". I am sure there is something to this especially where housing rent levels are suppressed through regulation as epitomised, for example, in the significant social housing stock at the heart of London.

However, with housing costs continuing to rise and with many governments selling off their social housing in expensive neighbourhoods and channelling tenants to lower-value areas, he adds that "this finding underscores the need for continued, and aggressive, development of attainable housing solutions".

I share the hope of many that the NSW government will embrace a "mixed communities approach" to the provision of social housing and not one which will target social housing at low-cost, low-density areas without a social mix and easy access to jobs and opportunities.

If they don't, inequity of access to the benefits of density and walkability will persist or worsen. The bonus of living in the "compact city" will increasingly go to those who need it least. That doesn't sound very Australian to me.