Turnout frog optimization through dynamic interaction modeling with revenue service wheel profiles

Railroad turnouts are critical track infrastructure elements which facilitate train movements between adjacent and diverging tracks. The turnout frog, in particular, induces significant wheel impacts as the wheel traverses through the turnout, which leads to frequent maintenance. To mitigate the wheel impact magnitude, this study analyzed the interaction between the wheel and frog using a three-dimensional (3D) explicit finite element (FE) models. The developed FE models were employed to quantify and compare the wheel impact magnitude between the wheel and the turnout frog. Three distinct frog geometries were investigated using five wheels representative of revenue service conditions to consider the worn profiles at three different speeds. The average wheel impact for each case was quantified for each wheel profile and weighted based on its percentage occurrence. The analysis revealed that the frog design with a gradual point slope, lower wing rail height, and longitudinal wing slope exhibited an average wheel impact load reduction of 46 % compared to the existing frog geometry during the wheel transition. This reduction can primarily be attributed to avoiding direct contact between the wheel tread and frog point for wheels in good condition. Additionally, introducing a longitudinal wing slope further reduced the wheel impact by an average of 21 % for hollow worn wheels by preventing the wheel from 'dropping' onto the point. However, the reduction in wheel impact was 20 % lower at a train speed of 100 mph (161 km/h) due to the wheel losing contact with the wing rail at the beginning of the longitudinal wing slope. Findings from this study contribute valuable insights for optimizing frog geometry to mitigate wheel impact, thereby enhancing the overall efficiency and maintenance of rail infrastructure.