Impact of lowering the maximum speed limit of city roads on pedestrian traffic accident patients: A nationwide before-and-after study.

Lee, Hun Gi; Kim, Jung Ho · 2025 · DOAJ

DOI: 10.1371/journal.pone.0325320

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Summary

This nationwide before-and-after study evaluated the impact of South Korea’s “Safe Speed-5030” policy, which lowered maximum urban road speed limits, on pedestrian traffic accident (P-TA) patients. Implemented on April 17, 2021, the policy reduced speed limits on urban general roads from 60–80 km/h to 50–60 km/h and on urban back roads from 40–60 km/h to 30 km/h. The study aimed to determine whether this intervention reduced the incidence and severity of P-TAs, providing evidence to inform potential policy modifications or abolition amidst public controversy. The researchers utilized data from the National Emergency Department Information System (NEDIS) for patients treated at level-1 and level-2 emergency medical centers in seven major South Korean cities. The study compared one-year periods before (April 2018–2019) and after (April 2021–2022) the policy implementation. The cohort included 26,842 P-TA patients, with demographic and clinical data collected via automated electronic medical records. Statistical analyses, including univariable and multivariable logistic regression, assessed changes in patient volume and risks of emergency surgery, intensive care unit (ICU) admission, and unfavorable outcomes (death or discharge without improvement), adjusting for confounders such as age, sex, and vital signs. The total number of P-TA patients decreased by 43.1%, dropping from 17,105 to 9,737. This reduction occurred across all age groups and accident times, though the decrease was less pronounced among geriatric patients (aged 60+) and those with severe injuries. While the absolute numbers of patients requiring emergency surgery, ICU admission, and experiencing unfavorable outcomes declined, multivariable analysis revealed that the adjusted risk of ICU admission (aOR 1.229) and unfavorable outcomes (aOR 1.344) significantly increased in the post-policy period. The risk of emergency surgery did not show a statistically significant difference. Notably, patients in their 70s experienced an increase in unfavorable outcomes, and the reduction in severe cases was significantly lower than in mild cases. The authors conclude that while the Safe Speed-5030 policy successfully reduced the overall volume of pedestrian accidents, its effectiveness was limited for vulnerable populations, particularly the elderly and severely injured. The increased relative risk of severe outcomes suggests that the policy may have disproportionately affected minor accidents while failing to adequately mitigate high-speed collisions involving vulnerable pedestrians. The study recommends revising the policy to better address specific high-risk groups rather than abolishing it entirely, highlighting the need for targeted interventions to protect geriatric pedestrians.

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• Empirical Findings: crash risk outcomes