Cul-de-sacs - crime and controversy

Road design and crime?

A recent email from a planner friend asked about reconfiguring a roadway: "I am working on rightsizing a suburban arterial. There have been some assaults and break ins. There is some speculation as to whether converting it from 6 lanes wide setbacks to 4 lanes with buildings up to the street will change this dynamic"

It made me think of other 6 lane, car-dominated cities. It also brought to mind some environmental criminology (EC) research supporting cul-de-sacs. The EC crowd is generally critical of New Urbanist designs for grid streets and increased neighborhood permeability.

The New Urbanism version goes like this: If we narrow the streets and avoid wide boulevards to slow car traffic we will encourage a more walkable street. If we use grid designs versus cul de sacs we can better provide walkable locations for people, activate neighborhoods, and make them safer.

The EC version goes like this: Grid layouts increase permeability and let more strangers through and that increases the risk of crime. That's why corner houses have more crime! Cul-de-sacs have less crime than grids for the same reason.

Not exactly.


Environmental criminology and burglary

What most EC studies actually show isn't patterns of crime. They show patterns of burglary. In fact the preponderance of EC studies (at least in the early years) were on burglary and theft versus robbery, interpersonal violence, shootings, gangs or drug crime - the crimes people fear most.

Still, EC's burglary-obsession should not detract from the point. Tantalizing answers emerge elsewhere; within the library of Problem Oriented Policing projects.

The POP library lists hundreds of projects on a wide variety of crimes. They describe both physical place-based prevention combined with social prevention. In most cases it was not physical tactics - design-out-crime - that did the trick. It was the  holistic ones that did, tactics that carefully considered context first and design impact second.

Curvilinear suburban road design - where do you walk?

Interestingly, one EC reviewer says this about context:

"Today, interior spaces within the home are dominant, and are commonly filled with electronic multimedia technologies and entertainment (also providing more opportunities for crime). The interior is now defined as the ‘leisure action space’ for both adults and children. This has led to exterior/public spaces being less used and this withdrawal has led to them being re-labeled and re-defined, often as ‘dangerous’ spaces."

Exterior spaces less used and defined as dangerous? If ever there was ever a context for New Urbanism, there it is!


Good design 

Good urban design should make exterior spaces less vacant, boring and unfriendly. It should create interesting walkable streets, places to go within walking distance, and a lively outdoors with ample social spaces for diverse people to socialize.

Urban guru Enrico Penalosa, and former mayor of Bogota during its widely-acclaimed redevelopment, finishes the thought: "The most dynamic economies of the twentieth century produced the most miserable cities of all. I'm talking about the U.S. of course - Atlanta, Phoenix, Miami, cities totally dominated by private cars."

"The most miserable cities are dominated by cars" - Penalosa