Rail Vehicle Model Dynamics of Motion Along Straight Track with Vertical Irregularity

During the long-term exploitation of railway tracks, possible changes in ground conditions may result in downgrading the quality of the drainage systems. Th e lack of adequate drainage of the track substructure leads to a lowering of the track formation cohesion ensured during the track construction phase as a result of ballast tamping. Th is potentially leads to pushing ballast into the subsoil, aff ecting the ballast which is present directly below the sleepers loaded during passage of the vehicles. As a result, the sleepers are no longer supported by ballast. Th e loss of support may aff ect a single sleeper or a set of neighbouring sleepers, depending of the length of the zone with inadequate drainage. Rail vehicle runs over such zones cause track vertical irregularities. Th is article is devoted to analysis of the infl uence of such irregularities on the rail vehicle dynamics. An arrangement model comprising a passenger coach and ballasted track was created with the VI-Rail tool. Coach runs were simulated within the range of operational speeds. Attention was paid to observation of the wheelrail contact forces, which appeared during runs over diff erent lengths of vertical irregularities. Th e obtained results are compared with currently binding criteria and regulations.