This is the 7790th most frequent Japanese word.
同線
"同線" (どうせん) refers to a route, line, or pathway shared or followed in common.
同線 is used here to refer to the same train line as previously mentioned in the conversation.
この電車は同線を通っています。
This train runs through the same line.
同線 here indicates a specific train or subway line that is being referred to, emphasizing efficiency.
同線を使えば、目的地に早く着くことができます。
If you use this line, you can reach your destination quickly.
同線 in this context metaphorically describes a shared route or path.