As a resident of Milwaukee, Wisconsin, a city that experiences the seasons in full force — winters with negative-20 wind chill balanced by summers spent lounging at the beach — I eagerly await the transition into summer. The warming temperatures means barbecues, concerts in the park, and longer days. However, as a health care worker, I’ve learned that summer also means something else: trauma.
The relationship between trauma and increasing temperature is well established. A recent study found that a 5 degree Celsius increase in maximum daily temperature was associated with a 1.8% increase in adult trauma admissions and a 10% increase in pediatric trauma admissions. And a 2023 meta-analysis found that interpersonal violence occurred much more frequently during warmer weather compared to cooler temperatures, with a 10% increase in aggravated assaults, 4% increase in robberies, and a 20% increase in homicides. A variety of factors have been hypothesized to account for the increase in trauma, including longer days, more leisure time, or being more active outdoors.
In addition to fluctuating rates of ED admissions and interpersonal violence, traffic-related injuries also increase with warming temperatures. While factors such as wind speed and precipitation vary based on geographic location, unsurprisingly, warmer weather has been associated with a higher rate of motorcycle collisions.
Numerous municipalities throughout the U.S. have sought to address the seasonal fluctuations in traffic-related injury rates with infrastructure investments to promote road safety. Vision Zero, an international strategy designed to eliminate all severe injuries and traffic-related fatalities, was first implemented in Sweden in the 1990s. Under this framework, the role of human error in the road system is acknowledged, and systems designers and policymakers engineer the roadway with an eye toward decreasing the severity of crashes rather than simply attempting to prevent collisions. This focus on prevention and mitigation, when applied clinically, is often relegated to primary care — but it’s important in surgical training as well. Just as it’s imperative to know how to treat the motorcyclist following a crash, so too should we be invested in minimizing the chance that the crash will happen in the first place.
As a framework, a variety of different policy interventions may fall under the Vision Zero umbrella. These include strategies to control speeds (whether through signage or environmental factors like speed bumps and roundabouts), separation of vehicles from pedestrians, and increasing visibility and conspicuity of pedestrians. Within Milwaukee, the need for Vision Zero interventions is undeniable: From 2013 to 2020, traffic related fatalities here tripled. And in the hospital, this reality is clear: as the summertime begins, those of us who work in the ED and trauma bay await the deluge of MVCs. Though members of all ages and communities are affected by traffic crashes, vulnerable street users like pedestrians, cyclists, and motorcyclists are more likely to be killed or seriously injured in crashes. I have seen the danger of roadways born out as a clinician, but also personally; while riding my bicycle, I was once hit by a driver running a stop sign. In an effort to address the issue, Milwaukee has made investments in road infrastructure — implementing separated bike lanes, road narrowing, and traffic calming measures in areas previously identified as at high risk.
Though the results of these city-wide measures are as yet unknown, overall, many of the interventions included in Vision Zero policies appear to reduce injuries and prevent traffic fatalities. Indeed, a meta-analysis assessing the efficacy of traffic calming measures found reduction in death in injuries within high-income countries, though further study was needed for low and middle income nations.
Despite these promising findings, prevalence of Vision Zero action plans remains relatively low in the U.S., with approximately 5% of small municipalities, 20% of medium sized municipalities, and 38% of large municipalities reporting Vision Zero plans in a recent study. And in locations with Vision Zero plans, these are not always implemented equitably. A 2017 analysis found that in New York City, interventions were least likely to be included in high risk, low-income areas. This is a missed opportunity, as such areas have the highest rate of fatalities: Another study assessing the efficacy of Vision Zero road projects among low income NYC residents found a decrease in injuries annually compared to surrounding counties, with reductions in hospitalizations, severe injuries, and an estimated $91 million decrease in Medicaid expenditures in the first five years after implementation.
Benefits aside, implementation of Vision Zero policies have not been without issue. Though reductions in injury rates were noted throughout the 2010s, the early years of the COVID-19 pandemic saw a reversal of many of these gains. Additionally, detractors suggest that though Vision Zero has been successful in many European nations, the cultural milieu and car-based infrastructure of the U.S. makes it unlikely that these policies would garner widespread national support. However, as a conceptual framework, Vision Zero does not call just for particular changes to be applied exactly throughout the country, but for a careful assessment of the needs of each individual community and what may work best there to improve safety.
As I drive home from work, I grumble about all of the construction and the impact on my commute. However, as I observe the elevated bike lanes and bump outs, I take solace in the infrastructure investments Milwaukee has made. Even though sometimes they may inconvenience me, sometimes a little inconvenience is worth making our communities safer.
What Vision Zero policies would you like to see implemented in your city? Share in the comments!
Marc Drake is a fifth-year resident in the Department of Otolaryngology and Communication Sciences at the Medical College of Wisconsin. His clinical interests include facial reconstruction, violence prevention, and the interplay between urban design and health care. Dr. Drake was a 2024–2025 Doximity Op-Med Fellow.
Illustration by April Brust
