Nice piece of work in the harvard gazette about this very topic: What makes a city thrive? I put some excerpts here.
The population density of Paris is about three times that of Boston. Does this mean Paris is three times as much fun as Boston, or that if Boston's population were compounded by three, it would become another Paris?
On Jan. 28, the Kennedy School's Rappaport Institute for Greater Boston in cooperation held a forum at Harvard to examine the concept of density and to look at ways it could be achieved.
"There's been an ongoing struggle to strengthen the city core, but not always to increase urban density. "
While it might not quite stack up to Paris, it can hardly be said that Boston is lacking in vibrancy. And yet, if present trends continue, there may be trouble ahead. Over the past 40 years, Boston's population has gone from 800,000 to 600,000.
According to the pro-density argument, urban institutions require a certain threshold population to support them. If not enough people want to shop or eat out, there won't be many good stores or restaurants. If the audience for music, theater, or art is small, these activities will not flourish. If the tax base is scanty, schools and municipal services will be substandard. Even parks need people to use them, and if the parks are deserted, they will not receive the upkeep they need to remain attractive.
Density is also considered good for the environment because it is easier and cheaper to provide heating, electricity, sewerage, and other services to people living in concentrated groups than to those in single-family homes in suburban areas. As a result, the impact of dense populations on the surrounding environment is less harmful.
If density is such a good thing, why haven't more people gotten the message? The first panel took up this question. David Parrish brought up the point that whether people want to take advantage of the social and cultural advantages of the city or seek the sprawling suburbs depends on where they are in the life cycle.
"A wise old man once told me, if you're looking for someone to have sex with, you live in the city; if you've got someone to have sex with, you live in the suburbs. Sometimes I think it may be as simple as that."
"Density used to be associated with poverty," said BSA President David Dixon
Alfred Wojciechowski, a principal in a Boston design firm, said that for density to work, people have to feel comfortable moving out into the public realm.
"It's very much about walkability. Goods and services have to be immediately available. You have to be able to walk to them."
In many cases, achieving greater density means building taller buildings, something that often proves unpopular, especially in the Boston area.
"We're an awfully conservative city when it comes to high buildings," said David Lee, a partner in a Boston architectural firm