Why city planners are killing the cul-de-sac

The cul-de-sac has been a staple of urban development — and families' real estate wish lists — for the last 50 years. Now some cities are banning them from new developments.

Why it matters: Street-network sprawl determines a city's energy footprint.

• Researchers have found that city and suburban streets have become less connected in ways that favor car travel over more climate-friendly options.
• Grid-like streets are better for walking, cycling and public transportation, while cul-de-sacs, three-way-intersections and gated communities with "one-way-out" routes encourage vehicle use.

What's happening: City planners are encouraging denser street grids in new communities and redevelopments, or they could place a tax on three-way-intersections, or a "cul-de-tax," to change street design habits, researchers Christopher Barrington-Leigh and Adam Millard-Ball write in a recent study published in the Proceedings of the National Academy of Sciences.

• In Denmark, bicycle and pedestrian paths are being integrated into communities to connect otherwise disconnected streets.
• National planning guidance in the United Kingdom called for connected streets over dead-end designs.
• After a 2001 earthquake in Bhuj, India, planners tried to interconnect all cul-de-sacs to avoid dead-end streets being blocked by fallen rubble.

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