Ballast deterioration inspection and quantification with 3D form method based on particle inscribed ellipsoid

Effective inspection of ballast deterioration is crucial in minimizing wastage of resources during track bed maintenance activities. However, existing studies on quantification and inspection of ballast deterioration often face challenges in application and inaccurate quantification indicators. To address the issues, a 3D form method based on the inscribed ellipsoid of a particle is proposed. This method captures the overall shape change during ballast deterioration and is modified to find the inscribed ellipsoid of irregular particles, validated using cubes. To compare the proposed form method with existing methods, tests were conducted using 30 fresh particles, and the effectiveness of the proposed form method in quantifying the overall shape was validated. A series of Los Angeles Abrasion test and scanning tests were also conducted to analyze the relationship between particle degradation and form from two perspectives: particle crushing and abrasion. The findings demonstrate that the proposed form method can effectively inspect the degree of ballast deterioration, particularly for high degrees of ballast deterioration. This study is significant for the future revision of ballast maintenance guidelines and the development of ballast deterioration inspection.