Ms Hodyl's fellowship paper, published last week, said construction of skyscrapers in central Melbourne should be supported, because a big jump in the CBD's population had many benefits for residents, including easy access to jobs, shops and entertainment. And it made the city "more lively and animated". But Melbourne had by far the fewest policies regulating apartment towers compared with the cities she studied. Her study also found that the social and economic consequences of such high-density development were "unknown", and were not required "to put Melbourne on the map as a global city". The paper warns that continuing planning policies supporting high-density CBD growth, and continued overseas investment, could have dire and long-lasting impacts.

"It will create a legacy of apartments that are of poor quality - homes that lack access to light, air and an outlook and that diminish the quality of the streets and parks below." There are no policies linking the density of developments in Melbourne to the provision of better public spaces. In other cities where high-rise living is common, developers see such trade-offs as the norm. In Vancouver, developers are allowed to cram high numbers of apartments into a project only if they agree to help fund construction of things such as parks, plazas, childcare centres, cinemas and performing arts spaces. In Melbourne, planning controls offer "cheap density" to developers, because they are able to ratchet up the number of apartments in a tower with only a very limited need to make any significant community contribution. "Not one of the five cities that I studied is choosing to develop in this way," Ms Hodyl concluded.

The study asked experts in each city to look at a block in Southbank, on City Road, which has 11 towers either built, approved or awaiting approval. The block could support 9200 residents when complete. Shown the density and height of the buildings on the block, one international planner recoiled. "This cluster of towers would never be built in New York," said Gary Lawrence, from engineers AECOM and former planning director for the city of Seattle. "The idea of creating a liveable city at this density is crazy." The report also looks at a block in Melbourne's CBD bounded by A'Beckett, Elizabeth, Franklin and Stewart Streets, where several towers are approved, being built or soon to be applied for. There are no enforceable laws on density or height on this block. It then takes these skyscrapers - where 8600 people would one day live - and contrasts them with what would be allowed in Hong Kong, New York or Vancouver. It finds that what is allowed in Melbourne would never be permitted in these cities. The report argues that Melbourne must establish far tighter CBD density controls; greater separation between towers; and far stricter apartment design standards. The city must also introduce "density bonuses" so developers can get "hyper-dense" apartment tower approvals only if they offset them with new open space or other benefits.

Ms Hodyl said too much attention had been given to the height of new skyscrapers. Far more important was the number of people living in a tower, whether apartments were high quality, and access to good parks and community services. An Andrews government spokeswoman said a new planning authority would work with the State Architect and Melbourne City Council on new high rises to "restore accountability" to CBD planning. Former planning minister Matthew Guy had made too many decisions "in secret behind closed doors", she said.