The effect of wheel and rail irregularities on the track

This paper reviews the effect of track irregularities and wheelflats in causing dynamic increments in wheel/rail force. The role of vehicle unsprung mass and track characteristics in governing the size of dynamic increments is examined and it is shown that for freight vehicles running over irregularities due to joints and welds, the dynamic forces should depend on the parameter MV2. The causes of irregularities in welded track are discussed and the importance of producing straight long welded rail is emphasised. Recent experimental and theoretical work on wheelflat impacts is described and the consequences of a wheelflat coinciding with P2 type forces due to joint or weld irregularities are considered.