Reducing the carbon footprint of metropolitan areas will require making them more compact in order to reduce driving or vehicle miles traveled (VMTs). Forgive me for saying this (density being a four letter word) but this will require increasing the density of existing communities and building new ones with appropriate density.
So what are the best ways to design compact, densely populated, walkable communities which are attractive, safe and lively? One thing clearly needed is enough housing so people live in the community; this is what creates the "24/7" communities which have been shown to be most successful over time. What are the best ways to do this while reducing crime and enhancing public safety?
Population density brings "eyes on the street" which generally reduces crime. It is better to walk around at night where other people are also walking, not down lonely alleys. More population density also supports more stores and activities -- movies, restaurants, and the like -- which bring lights, life and more people. One of the biggest mistakes of many new suburban town centers is the failure to include enough housing, with the result that there are not enough people to support the stores and restaurants needed to keep the center economically and socially vital.
The only way to bring in population density is to build up. Single family homes, even town homes lined up side by side with party walls, do not give the density in a walkable range to support stores and services and have eyes on the street. It takes apartments and condos to do that. This means at least mid-rise construction, and in some places true high rise buildings.
This at least is the conventional thinking, which is now being challenged. In a recent article in the Washington Post by Tim Harford, Want to Cut Crime? It Takes a Neighborhood, Harford reports that
"Two new-wave economists, Edward Glaeser of Harvard and Bruce Sacerdote of Dartmouth, matched crime figures with data on building height and discovered that the residents of high-rise apartments are much more likely to be victims of crime -- specifically street crime. The effect remains similar after statistically adjusting for poverty, demographics and public housing: It's the height of the building itself that matters."
Pardon me if I remain unconvinced. Does this mean that we need lots of people on the streets but no where for them to live? At what building height does safety begin to diminish? And why do low rise buildings make people more conscious of the street and more likely to intervene in an incident? What if they do not happen to be sitting on the front stoop, but are in the back in the family room watching TV?
And the biggest conundrum of all -- if high rise buildings make people less safe, why is New York City the safest large city in America and one of the safest cities of all sizes based on the FBI's most recent crime data? New York is, after all, the quintessential city of high rises.
It would seem that we still have some sorting out to do to figure out the relationships among density, housing design, safety and community vitality and viability. Given the importance of reducing VMTs in order to cut the 18% of all U.S. carbon emissions that come from cars and SUVs, this would be a good time to develop clarity on these issues as we build ever more compactly in the years ahead.
