(NEW YORK) -- Philadelphia resident Latanya Byrd's 27-year-old niece Samara Banks and three of Banks' sons were struck and killed by a speeding driver in 2013. They were crossing Roosevelt Boulevard, a 12-lane road that passes through some of the city's most diverse and lowest-income neighborhoods.
"It was just so devastating," Byrd told ABC News. "We lost two generations in one swoop. I mean, just an instant snap of the finger."
As the local population has swelled, Byrd said outdated transportation infrastructure -- grass paths instead of pavements, dangerously short pedestrian signal cycles, overcrowded bus stops, to name a few -- can partially explain why this road is one of America's deadliest.
Byrd's story exemplifies a larger trend of racial disparities and inequity in traffic fatalities, as reported by the Governors Highway Safety Association and National Highway Traffic Safety Administration last year.
And a new study published in the American Journal of Preventive Medicine last week reveals that these disparities may be even wider than initially estimated, especially for "vulnerable" modes of travel such as walking and cycling.
Previous estimates were derived by calculating national traffic fatality counts by race and ethnicity across travel modes, sometimes adjusting for the population of each racial and ethnic group.
"But that assumes that everyone of all races and ethnicities cycle, walk or drive the same number of miles, and that we find is not true," Matthew Raifman, a Boston University School of Public Health doctoral candidate who co-authored the new study, told ABC News.
Using 2017 national traffic fatality and household travel data, Raifman and co-author Ernani Choma, a research fellow at the Harvard T.H. Chan School of Public Health, analyzed the travel activity of different racial and ethnic groups by the additional variables of travel mode, distance traveled, time of day and urbanicity.
They found that when examining only car drivers or passengers, the traffic fatality rate per mile traveled was 1.8 times higher for Black Americans than white Americans.
That rate increases to 2.2 times and 4.5 times when considering only pedestrians and cyclists, respectively.
The rates for Hispanic Americans follow similar, though less severe, patterns. Asian Americans had the lowest fatality rates across all modes of travel.
During the nighttime, racial and ethnic disparities in traffic deaths were exacerbated.
Byrd partially attributed these disparities to systemic underinvestment in protected walking and cycling infrastructure in working class neighborhoods, which are disproportionately communities of color -- while most road repairs occur elsewhere.
"It can be the same road that's getting fixed every year, and it's nowhere near as bad as the roads in the lower-income section of the city," she said.
The fact that Black and Hispanic Americans die at higher rates due to traffic accidents yet bike and walk fewer miles in aggregate is a problem in itself, Choma told ABC News.
"It might indicate that, for example, Black Americans or Hispanic Americans are less able to cycle, they don't have access to transportation in that way," he said. "Maybe it's less bike lanes. Maybe they don't even bike because they feel unsafe."
Raifman said their analysis could also indicate racial inequity in the medical service chain -- emergency response times, quality of care, access to health insurance and pre-existing conditions.
"Traffic fatalities don't necessarily occur at the point of the collision," he said. "Some people die in a hospital or an emergency room or en route to an emergency room."
Choma added that without safe access to bike lanes and pedestrian crossings, Black and Hispanic Americans also lose out on the health benefits that come from physical activity, as well as the environmental benefits like reducing air pollution.
Byrd co-founded the advocacy group Families for Safe Streets Greater Philadelphia to confront the "epidemic" of traffic violence. She successfully lobbied for automated speed cameras, which were placed at eight intersections on Roosevelt Boulevard in June 2020.
The U.S. Department of Transportation created the Safe Streets and Roads for All program in May to allocate federal transportation funding to cities and local governments. President Joe Biden also recently signed the Infrastructure Investment and Jobs Act, providing $550 billion in spending on roads, bridges, transit and more.
With more complete data on specific streets, walking and cycling activity levels, as well as other social costs of traffic crashes, like injuries and property damage, Raifman and Choma said they hope future research will spur local policymakers to address the root of racial disparities in traffic deaths.
"We have these two big challenges. We have structural racism, and we have traffic fatalities, and they're related. They're interlinked," Raifman said. "Instead of just investing in reducing traffic fatalities, why not do it in a way that's also addressing the systemic, structural racism challenges in our society?"