tracks per inch

例句：

1. 1. The train has a capacity of 500 tracks per hour.
   这列火车每小时有500个轨道。
2. 2.The construction crew is responsible for maintaining the tracks per mile.
   施工队负责维护每英里的轨道。
3. 3. The new rail line will increase the number of tracks per mile in the area.
   新的铁路线将增加该地区每英里的轨道数量。