To improve rail conditions on the Tokaido Shin-kansen line, studies on worn rail profiles and rail damage are first presented and the causes of damage assessed. Then the abrasion of rail corners on tangent track is taken up. Through the study of contact points between wheel and rail with the use of a coordinate transform, the fact that the lateral movement of bogies is accelerated by tilting of the rail is made clear. On the basis of these findings, new measures such as limiting the displacement of contact points between wheel and rail, cutting off neighbouring parts of the running fringe, having the rail head side conform to the tyre profile and cutting off the gauge corner on curves with larger radius and on tangent track are proposed, and a new rail profile with full use of grinding is designed.