By Heather Mase, Graduate student in Georgia Tech’s School of City and Regional Planning and Research Assistant with the Friendly Cities Lab, guest blogger
In the past decade, nearly half of all Atlanta’s reported pedestrian-involved vehicle collisions occurred within 100 feet of a signalized intersection. One in ten resulted in serious injuries to pedestrians — or death. In real numbers, since 2013, at least 178 pedestrians have been seriously injured and 40 have been killed in Atlanta’s intersections.
Even one traffic-related fatality is too many, and as Atlanta works towards achieving its Vision Zero goals, improving safety at intersections is critical.
Of a handful of measures proven to make signalized intersections safer, one stands out. And that’s the leading pedestrian interval.
Leading pedestrian intervals explained
The way it works is simple. Leading pedestrian intervals, or LPIs, turn on the walk signal at least three seconds before drivers get a green light. That means that for those three seconds, pedestrians get to start crossing the street before left-turning cars go — they get to “lead.” This brief but crucial head start improves pedestrian visibility and safety considerably, by reducing possible collisions with turning vehicles.
Image Credit: NACTO, Urban Street Design Guide, 2013
Here in Atlanta, the City has taken action to improve pedestrian safety at intersections by installing 149 LPIs across the city. Atlanta has focused these efforts on areas like Midtown and Downtown, neighborhoods with a high volume of pedestrian activity. However, given that more than 800 intersections across the city remain without any signal-based pedestrian safety improvements, a key question arises:
Where should LPIs be prioritized in Atlanta?
To decide where to direct resources, traffic safety analyses typically rely on three to five years of historical collision data from police reports. But this approach is inherently reactive, requiring analysts to wait for collisions to occur in order to examine the measures that could prevent them.
A proactive, systemic approach to safety
To take a more proactive approach to pedestrian safety, I developed a framework to analyze and rank Atlanta intersections, taking into account factors like road design, pedestrian demand, and equity. (Read a more technical explanation of the process used here.)
Many of the highest priority intersections for LPIs are concentrated in just two parts of town: 1. within two miles of Downtown, and 2. in the west Atlanta area.
Each of the top 25 highest-priority intersections saw at least one pedestrian fatality or serious injury between 2013 and 2022. Most also have hostile designs for pedestrians, are close to places with high pedestrian activity, and are in neighborhoods with a high proportion of people of color and low-income households.
Top 25 high-priority intersections
Final LPI ranking prioritization results map
We shouldn’t wait for tragedy to make our intersections safer
We can learn by studying the places where collisions have happened. But if we already know an intersection is dangerous, then there is no reason to wait for collisions to take place to fix it. The LPI is a fairly low-cost, easy fix that has proven to be a promising avenue to prioritize and protect the most vulnerable people on our roads.