Dense areas are safer but road design is critical

By Chris McCahill

Dense development patterns offer important safety benefits, according to new research from the University of Pennsylvania, but high-speed roads in dense suburban centers are deadly for pedestrians. This new study confirms what others have already shown—that attention to context is critical to safe road design.

This newest study draws on fatal crash data from 2010 to 2014 in greater Philadelphia. The region’s densest areas experienced lower crash rates, according to Plan Philly, which the study’s author, Erick Guerra, largely attributes to lower speed roads. But in dense suburban centers with roads designed primarily for car travel, pedestrians were at the greatest risk, even while drivers reaped safety benefits. Pedestrian deaths are a growing systemic problem across the U.S.

“It’s evidence that a more sprawling and exurban growth pattern is going to be more dangerous,” explained Guerra. “And it should show where we want to concentrate pedestrian-safety features.”

This study echoes and builds on earlier studies that point to the importance of integrated land use and road design policies for traffic safety. For instance, a 2011 study of 24 cities in California by University of Connecticut researchers revealed areas with the densest street networks experienced 70 percent fewer fatal crashes than average, which the authors attribute mainly to slower vehicle speeds. And Dangerous by Design, released earlier this year by Smart Growth America, shows pedestrian risks are greatest—especially for low-income communities and people of color—in many areas with roads designed primarily for car travel.

Chris McCahill is the Deputy Director at SSTI.