Infrastructure matters: A systematic review of bicycle infrastructure design influencing cycling crash and injury risk

Introduction: This study systematically reviews empirical research on urban cycling infrastructure design and its effects on cycling safety. Utilizing the PRISMA framework, the review synthesizes findings from peer-reviewed studies collected from major databases, ultimately incorporating 104 high-quality articles. Method: The primary contribution of this research addresses three essential questions. First, it identifies and critically assesses significant design elements, including physically separated cycle tracks, optimized intersection configurations, and tailored signal timings, that have demonstrated both positive and negative impacts on cycling safety. Secondly, the study explores the diverse array of safety metrics, analytical tools, and data sources used within existing literature. Traditional safety indicators, such as collision and injury rates, are discussed alongside surrogate safety measures and emerging digital data sources. This comprehensive synthesis highlights current advancements as well as persistent challenges, including inconsistent data granularity and systematic underreporting of incidents not involving motor vehicles. Thirdly, the review critically evaluates the methodological, theoretical, and practical obstacles that complicate the rigorous assessment of cycling infrastructure safety. Specific challenges discussed include the discrepancy between perceived and actual safety, complexities in controlling for confounding factors, and the limited availability of standardized evaluation frameworks. Results: Based on these insights, the study recommends future research directions focused on multidisciplinary collaboration, enhanced data integration, and methodological innovation to address existing knowledge gaps. Ultimately, the review provides a nuanced understanding of how urban built environment features influence cycling safety, providing evidence-based guidance to inform infrastructure planning and policy-making. Practical Applications: These findings aim to support academic inquiry and practical efforts dedicated to reducing cycling-related injuries and fatalities.