<p>Efficient train operation relies on optimal traction at the wheel–rail interface, which can be compromised by factors such as water and/or contamination (e.g. leaf, sand, oil, and surface abrasion debris). This study introduces a finite element model to assess adhesion enhancement at the wheel–rail interface, with a focus on the impact of sand particles during the sanding process. Surface roughness is initially introduced to quantify its effect on adhesion, followed by the inclusion of rail plastic deformation. By integrating these two factors, the model provides a comprehensive framework for evaluating the complex mechanisms influencing adhesion at the wheel–rail interface, particularly in real-world train operations where surface conditions interact with contaminants such as sand fragments. This approach addresses the existing gap in understanding how rail surface condition and rail plastic deformation contribute to adhesion enhancement during the sanding process, offering new insights for optimising railway maintenance strategies.</p>