A data-driven framework for assessing horizontal curve safety using friction and reliability analysis: a case study on an Indian highway

R. Srinivasa Kumar; Vemula Rajesh Kumar

doi:10.55329/uzno7733

Authors

R. Srinivasa Kumar Osmania University, India https://orcid.org/0009-0005-0286-3568
Vemula Rajesh Kumar Osmania University, India

DOI:

https://doi.org/10.55329/uzno7733

Keywords:

advisory speed prediction, global sensitivity, reliability analysis, safety index, Southern Asia, low- and middle-income countries (LMICs)

Abstract

Horizontal curves are frequently associated with elevated crash risk because of the combined effects of vehicle speed, roadway geometry, and tire–pavement friction. This study examines these interactions using field data collected from five horizontal curves on NH-340C in India. An empirical model for estimating the maximum available side friction was developed using measured vehicle speeds, superelevation, and pavement surface texture represented by Mean Texture Depth (MTD). Curve safety was evaluated using three complementary indicators: the Safety Index (SI), Change in Safety Index (ΔSI), and Dynamic Curve Safety Index (DCSI), which together describe local stability conditions and safety variations along the curve. The calibrated friction model shows a decrease in available friction with increasing speed and a moderate increase with pavement texture, producing values in the range of 0.16–0.28 that are consistent with international design guidelines. Model reliability was evaluated using uncertainty and sensitivity analysis techniques, including the delta method, bootstrap resampling, the First-Order Reliability Method, and global sensitivity analysis using Sobol and Morris approaches. The results indicate that pavement texture and operating speed are the dominant factors influencing friction variability, while superelevation has a comparatively smaller effect. In addition, a regression-based model was developed to estimate mid-curve operating speeds, which can support the determination of advisory speeds for curve safety management.

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Author Biographies

R. Srinivasa Kumar, Osmania University, India

R. Srinivasa Kumar is a Professor in the Department of Civil Engineering at the University College of Engineering, Osmania University. He obtained his B.E. in Civil Engineering and M.E. and Ph.D. degrees in Transportation Engineering. His research interests include traffic engineering, pavement engineering, highway safety, and ITS. He received the IRC Commendation Certificate for a best research paper and the Best Teacher Award from Institution of Engineers (India). He has served as a technical expert for rural road programs under PMGSY while working at Banaras Hindu University. Dr. Kumar has authored seven books on transportation and highway engineering published by Universities Press and has extensive experience traffic analysis, road safety, and transportation planning.

CRediT contribution: Conceptualization, Methodology, Software, Supervision, Writing – original draft, Writing – review & editing.

Vemula Rajesh Kumar, Osmania University, India

Vemula Rajesh Kumar is a transportation engineering researcher specializing in road safety analysis, with particular focus on safety performance at horizontal curves. He holds an M. Tech in Transportation Engineering from Osmania University. His research interests include geometric design of highways, crash analysis, traffic safety evaluation, and the development of engineering solutions to reduce accidents on curved road sections.

CRediT contribution: Data curation, Formal analysis, Investigation.

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