Like any highway system, the federal airways have their maintrunkline.
同任何公路系统一样，联邦航空线路也有其主航线。
2
These gathering systems are normally owned by the pipeline company that operates the maintrunkline.
集油管道系统和原油干线管道常归管道公司所有。
3
Then divides the highway network into four levels: maintrunkline, sub-trunk, feeder and connecting line, and also positions functions of the four levels.