SoylentNews

Hugh Pickens writes:

Angie Schmitt writes in Streetsblog USA that city streets with the widest lanes — 12 feet or wider — are associated with greater crash rates and higher impact speeds and that there is hard evidence that wider lanes increase risk on city streets. Dewan Masud Karim conducted a wide-ranging review of existing research as well as an examination of crash databases in two cities, taking into consideration 190 randomly selected intersections in Tokyo and 70 in Toronto. Looking at the crash databases, Karim found that collision rates escalate as lane widths exceed about 10.5 feet. According to Karim "human behavior is impacted by the street environment, and narrower lanes in urban areas result in less aggressive driving and more ability to slow or stop a vehicle over a short distance to avoid collision. Designers of streets can utilize the “unused space” to provide an enhanced public realm, including cycling facilities and wider sidewalks, or to save money on the asphalt not used by motorists." Karim concluded that there is a sweet spot for lane widths on city streets, between about 10 and 10.5 feet.

According to Jeff Speck the fundamental error that underlies the practice of traffic engineering is an outright refusal to acknowledge that human behavior is impacted by its environment and it applies to safety planning, as traffic engineers, designing for the drunk who's texting at midnight, widen our city streets so that the things that drivers might hit are further away. "When lanes are built too wide, many bad things happen. In a sentence: pedestrians are forced to walk further across streets on which cars are moving too fast and bikes don't fit," writes Speck adding that a pedestrian hit by a car traveling 30 mph at the time of impact is between seven and nine times as likely to be killed as one hit by a car traveling 20 mph This tremendously sharp upward fatality curve means that, at urban motoring speeds, every single mile per hour counts. "Every urban 12-foot lane that is not narrowed to 10 feet represents a form of criminal negligence; every injury and death, perhaps avoidable, not avoided—by choice."