The End of the Cul-de-Sac?
Photo: Connecticut Smart GrowthThe cul-de-sac is perhaps the quintessential symbol of suburban America. Perhaps millions of them have paved over greenways throughout the country. Hailed for their safety (no traffic that can run over kids) and prized by developers because they allow more houses to be built into oddly shaped tracts and right up to the edges of rivers and property lines, planners and town officials are beginning to realize their downside.
Early last year the state of Virginia became the first state to severely limit cul-de-sacs from future development. Similar actions have been taken in Portland Oregon, Austin, Texas, and Charlotte, North Carolina. What they are beginning to realize is that the cul-de-sac street grid uses land inefficiently, discourages walking and biking, and causes an almost complete dependence on driving, with attendant pollution and energy use. Furthermore, town officials are beginning to realize that unconnected streets cost more money to provide services to and force traffic onto increasingly crowded arterial roads, which then, in many cases, need to be widened (more tax money).
Two interesting studies were presented at the CNU Transportation Summit in 2008 that examined the public safety and financial implications of street
connectivity. They both seem to support what critics have begun to voice about the downside of cul-de-sac’s grid networks. The first study was conducted by Norman Garrick and Wesley Marshall, of the University of Connecticut’s Center for Transportation and Urban Planning. Their study investigated the relationships between connectivity, network configuration, density, severe vehicle crashes, and mode choice.
