The low adhesion behavior of wheel/rail under oil contaminated conditions and the effect of spraying sand were tested at high speeds on a rolling contact fatigue twindisc testing machine.The influences of test speeds,creepages,axle loads and spraying sand on the adhesion coefficient were studied under the maximum test speed of 200 km/h.The results show that with the increase of the creepage,the adhesion coefficient is first increased,then decreased slightly and further tends to be stable,and the maximum occurs at about 3% creepage.As the test speed increases,the adhesion coefficient is decreased quickly,e.g.,the maximum adhesion coefficient is decreased from 0.092 to 0.049 when the speed is increased from 50 km/h to 200 km/h.When the tested axle load is increased from 12 t to 16 t,the adhesion coefficient is only increased by 001.After spraying sand,the adhesion coefficient is about 3 times of that without spraying sand,and it still decreases with the increase of speed.Spraying sand causes a lot of pits on the wheel/rail surface after the test,which will increase the surface roughness and play a role in the adhesion enhancement.However,the spraying sand will damage the contact surface,which will promote the initiation of rolling contact fatigue under certain conditions and threaten the running safety.