New Research from Incheon National University Reveals the Key to Road Safety 

New study demonstrates, pedestrian and roadside facilities—modifiable during maintenance—reduce crashes more effectively than fixed geometric road design attributes

New research from Incheon National University highlights that pedestrian and roadside facilities—modifiable during maintenance, such as sidewalks, crossing facilities, and street lighting—play a critical role in reducing crashes rather than geometric attributes that are fixed on the road design stage. The study suggests that road safety is shaped by the interaction of various design attributes, with safety outcomes influenced by dynamic factors like volumes and speeds.

Image title: Understanding the Impact of Road Design and Traffic Conditions on Crash Likelihood

Image caption: Researchers demonstrate the importance of pedestrian and roadside facilities in reducing crash likelihood, highlighting the dynamic interaction between road design elements and traffic conditions for safer, more effective road safety interventions.

Image credits: Dr. Wookjae Yang from Incheon National University (INU), South Korea

License type: Original content

Usage restrictions: Cannot be reused without permission

Road traffic crashes remain a significant global issue, with over 1.19 million fatalities and millions more injured annually. The World Health Organization (WHO) has set a target to halve these deaths and injuries by 2030, emphasizing the need for a holistic approach to road safety. While road design improvements, such as pedestrian crossings, are critical in enhancing safety, understanding the complex interactions between road attributes and traffic conditions is often overlooked.

To address this gap, researchers from Incheon National University, led by Assistant Professor Wookjae Yang, conducted a study examining how different road design elements and traffic conditions interact to affect the likelihood of crashes. Using data from a 68-kilometer segment of a national highway in South Korea, the team applied principal component analysis (PCA) and piecewise structural equation modeling (PSEM) to examine both direct and indirect effects of road attributes on two major crash types: head-on and run-off crashes. This study was made available online on February 20, 2025, and published in Volume 93 of Journal of Safety Research on July 1, 2025.

The team categorized road attributes into three principal components: PC1 (pedestrian and roadside facilities), PC2 (cross-section and intersection conditions), and PC3 (road surface and curvature conditions). “Unlike prior studies that treated traffic speed and volume as static control variables, our study considered them as mediating factors—highlighting how road conditions affect crashes not just directly but also through their influence on traffic behavior,” explains Dr. Yang.

The results showed that PC1 had the most substantial direct effect on crash outcomes, particularly for run-off crashes. “Elements such as sidewalks, street lighting, and pedestrian crossings—which are comparably easier to modify during maintenance—proved more influential in reducing crashes than fixed geometric elements established at the design stage,” adds Dr. Yang. Inadequate pedestrian and roadside facilities were associated with higher vehicle speeds, indirectly increasing the likelihood of both crash types.

In contrast, PC2 and PC3, which include design features such as intersections, lane width, and curvature, did not show significant direct effects on crash frequency. Researchers suggest this may be due to the relatively uniform standards followed in national highway segments, leaving limited variation in these features across the study sample. However, both components did exert indirect effects through speed and volume, reinforcing the idea that safety outcomes are shaped by the interaction of multiple factors rather than any single design attribute.

The study offers practical implications for transportation agencies and policymakers. It suggests that road safety strategies should prioritize modifiable operational features, such as pedestrian infrastructure and roadside objects, which can be adjusted post-construction to improve safety. Furthermore, refining global road assessment tools such as International Road Assessment Programme’s (iRAP) to separate fixed geometric features from alterable operational elements may lead to more targeted and cost-effective safety interventions.

Overall, these findings contribute to a more nuanced understanding of crash dynamics and emphasize the value of context-sensitive design and maintenance approaches. “By demonstrating the mediating role of traffic volume and speed, and highlighting the stronger influence of pedestrian and roadside facilities over fixed design features, the study offers actionable insights for more effective road safety interventions,” concludes Dr. Yang.

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About Incheon National University

Incheon National University (INU) is a comprehensive, student-focused university. It was founded in 1979 and given university status in 1988. One of the largest universities in South Korea, it houses nearly 14,000 students and 500 faculty members. In 2010, INU merged with Incheon City College to expand capacity and open more curricula. With its commitment to academic excellence and an unrelenting devotion to innovative research, INU offers its students real-world internship experiences. INU not only focuses on studying and learning but also strives to provide a supportive environment for students to follow their passion, grow, and, as their slogan says, be INspired.

Website: https://www.inu.ac.kr/sites/inuengl/index.do?epTicket=LOG

About Dr. Wookjae Yang from Incheon National University, South Korea

Wookjae Yang is an Assistant Professor of Urban Policy and Administration and Director of City Analytics + Planning Policy (CAPP) lab at Incheon National University. His group leverages urban data science and innovative research methodologies to address challenges cities face at the intersection of land use, transportation, and smart technology. His group constructs academic foundations for providing evidence-based policy interventions that drive meaningful change in our society while achieving smart growth. In 2023, Wookjae Yang received a PhD in Urban Planning from University of Utah.