A seven-second head start for pedestrians crossing the street reduced injuries in New York City (NYC) by a third, according to a study of more than 6,000 intersections.

Leading Pedestrian Intervals (LPIs) give pedestrians several seconds to begin crossing before vehicles get a green light. Typically, these intervals are between 7 and 11 seconds depending on the size of an intersection.

The reduction in pedestrian injuries was consistent across all intersection types. The most pronounced impact was seen during the daytime. Fatal pedestrian crashes dropped 65 percent during daylight hours, according to researchers at Columbia University Mailman School of Public Health.

Findings from the study, Effectiveness of leading pedestrian intervals for city walkers’ safety, were published in Nature Cities.

Researchers evaluated intersection-level injury risk from 2013 to 2018 using a spatial ecological panel design. It used precise geographic data from NYC Open Data and the city’s Vision Zero initiative. There were 2,869 LPI treatments installed at intersections studied. It is the largest dataset to date evaluating LPI effectiveness.

“Most pedestrian-vehicle crashes happen near the curb, where drivers are less likely to see people crossing,” lead author Christopher Morrison, Ph.D., assistant professor of epidemiology at Columbia Mailman School, said.

“LPIs are one of the most affordable and scalable traffic safety interventions. A 7-second delay for drivers can mean the difference between life and death for pedestrians. Our findings show they work—and could be adopted more widely.”