Buld a better city

Writing in today's WSJ, eminent architect and planner Moshe Safdie worries about densities in Manhattan, "How to Build a Better City ... How crowded should or can cities get? What should be driving tower design?"  He begins this way:

The flurry of high-rise tower construction now under way in New York will bring about a quantum leap in density, one that will forever change our urban environment. The city is now home to seven of the 100 tallest buildings in the world. The current building campaign will produce five more. They are a reminder that towers have become the dominant building type in most major cities around the world, increasing congestion as they accumulate.

These developments raise fundamental questions: How crowded should or can cities get? What should be driving tower design, be it residential, commercial or mixed use? Are our current planning and zoning regulations adequate in guiding this growth, in mitigating the impact of density? Or do we need new tools for a new era of mega-scale construction? Finally, towers create fundamental questions about the nature and character of the public realm.

Neither the prevailing tower designs nor current planning practice world-wide are able to cope with the new reality

First some quibbles about facts.  Manhattan was far denser in years past. Wikipedia dates the high point over 100 years ago. We get into these debates because the data exist for spatial aggregates and we are obliged to use large-area averages.  I have noted many times that Los Angeles' urbanized area has (for some years) had a higher population density than New York's.

High rise towers do create externalities, some positive and some negative. These discussions always bump up against issues of scaling. World class designers like Safdie are great at coming up with designs for buildings and site plans for collections of buildings and spaces. But none among us can tackle (design) whole cities or whole Manhattans. The complexities are too vast. If there is to be a top-down plan for all of Manhattan, it must be a minimalist, one that leaves room for designers like Safdie to create great site plans.

Safdie cites an example: "Qinhuangsao, a Chinese city of three million people, has a local ordinance that requires that three hours of sunlight, as measured in the winter solstice, must each each apartment."  OK, but by all means allow development rights to be tradeable. If there is an overachiever developer who allows more sunlight, let him build somewhere else in the same city but with a reduced sunlight requirement.  He would bid (use up his rights or buy some) to do so if he had a powerful reason, including the economic benefits of higher density. There has to be a way that the widely dispersed bottom-up wisdom of large numbers of site developers can enter the big plan.