Complex sentence: The system serves most of the Seoul Metropolitan Area including the Incheon metropolis and satellite cities in Gyeonggi province and crossing large rural areas to reach major cities in northern Chungnam province and western Gangwon province that lie over 100km away from the capital.
Split into simpler sentences: The system serves most of the Seoul Metropolitan Area including the Incheon metropolis and satellite cities in Gyeonggi province. Some lines in the network cross large rural areas to reach major cities in northern Chungnam province and western Gangwon province that lie over 100km away from the capital.