Impact assessment for bicycle highway on cyclist’s PM2.5 exposure: Evidence from Beijing

Abstract

Elevated bicycle highways are increasingly piloted to enhance the efficiency and safety of cyclists, yet their impact on air pollution exposures remains underexamined. This study assessed the effectiveness of bicycle highways in reducing exposure to particulate matters (PM_2.5) in Beijing, China. Real-world measurements were conducted along three representative cycling routes connecting same working and residential areas, that is, route bicycle highways (RB), route arterials (RA), and route collectors (RC). Compared to RA and RC, RB are slightly longer (3.86% and 7.71%, respectively) but offer shorter travel times (1.28% and 4.79%, respectively). Notably, vertical-separated paths on RB significantly reduce concentration by up to 23.08% compared to vegetation-protected lanes. Although higher concentrations are observed near construction sites and transportation facilities, the absence of intersections on RB reduces exposure by 5.47% and 6.75% compared to RA and RC, respectively. A notable disparity between exposure hotspots and heavily polluted areas highlights the complex interactions of external factors, such as meteorological conditions, traffic patterns, and built environments. Linear and non-linear regression analyses (via OLS and XGBoost–SHAP) elaborate the significant contributions of meteorological conditions, traffic patterns, road design, and land use in shaping on-road exposures. These findings suggest the urgent need for an exposure-focused evaluation approach in bicycle infrastructure planning. By considering the complicated effects caused by these external factors, policymakers can develop targeted strategies to mitigate exposure risks and promote safer and healthier cycling environments.