Description

This introductory technical paper outlines the initial conceptual framework and proposed scope for modeling vehicle tire wear and consumption in the HDM-4 highway evaluation model. Written during the early phase of the International Study of Highway Development and Management Tools (ISOHDM), the report reviews legacy tire algorithms from HDM-III and identifies key limitations in predicting modern tire performance, particularly regarding radial construction, synthetic rubber compounds, and advanced tread patterns. The document defines the primary objectives of the new tire model: to establish mechanistic-empirical relationships between road condition parameters (roughness, surface texture, geometric alignment) and tire life, retreadability, and replacement costs across full vehicle fleets. Basic force balance equations are proposed, isolating the impacts of road gradient, horizontal curvature, vehicle speed, and pavement roughness on tread abrasion. In addition, the report highlights the data collection requirements for global calibration trials, outlining field survey protocols for monitoring tread depth loss in commercial transport fleets across diverse climatic zones. This baseline paper established the foundation for subsequent technical working groups to refine vehicle operating cost (VOC) calculations and standard software routines within the broader HDM-4 system architecture. Overall, the report emphasizes rigorous empirical validation, standardized data acquisition protocols, and modular integration into the broader Highway Development and Management analytical engine. By combining physical principles with statistical calibration across international trial sites, this working paper provides a robust theoretical and practical baseline for highway authorities to evaluate long-term infrastructure policy options, allocate maintenance budgets efficiently, and maximize economic returns across regional and national road networks.