保证列车间隔时间进行线路养护工作是日本国营铁路繁忙干线上的重要问题之一。但是,在每天一条线上行驶150～200次客货列车的非常繁忙干线上,要保证足够的列车间隔时间来更换长钢轨,常是非常困难的。因此,日本国铁在东北线上试行集中换轨的办法,使用了大量工人、大量材料,有效地换下许多旧轨并迅速使轨道得到加强。 It is one of the important issues on the busy trunk line of the Japanese state-owned railways to ensure line maintenance work at train intervals. However, on very busy lines that carry 150 to 200 passenger and freight trains on a daily basis, it is often very difficult to ensure sufficient train intervals to replace long rails. As a result, the Japanese National Railways piloted a concentrated exchange of track on the northeastern route, using large numbers of workers, large quantities of materials, effectively replacing many old railways and rapidly accelerating the orbit.