Research Materials from Professor Uk-jae Yang’s Research Team

A study conducted by a research team led by Professor Uk-jae Yang (corresponding author) of the Department of Urban Administration at Incheon National University, with Byung-wook Kang, an undergraduate student in the same department, as a co-author, has been published in Transport Policy, a leading international journal in the field of transportation (IF = 6.3, top 5% in JCR).

The study, titled “Slower Roads, Cleaner Skies? Causal Effects of Speed Limit Reduction on Urban Air Quality Using Propensity Score Matching and Spatial Difference-in-Differences Regression,” analyzes the impact of the “Safe Speed 5030” policy, which was fully implemented nationwide in 2021, on air quality using quasi-experimental research methods.

The findings show that while the policy had a clear positive effect on SDG 3.6 of the United Nations Sustainable Development Goals—reducing deaths and injuries from road traffic accidents—it also revealed a policy trade-off. Specifically, frequent acceleration and deceleration to comply with speed limits led to increased pollutant emissions, resulting in no significant improvement in urban air quality, corresponding to SDG 11.6, which aims to reduce the environmental impact of cities.