Here are the four lines in the same stanza:
裂けて 避けた 鈍行列車
点いて 消える きまぐれ信号
直せ 叩け 切り換えスイッチ
歪み 並ぶ 使い捨てのレール
Do you see the "verb + verb + (topic) noun" pattern on each line? Essentially these lines are a list of four nouns, just like "parsley, sage, rosemary and thyme." I don't think it's a good idea to suddenly assume the train as the subject of the fourth line. The express train is going back to a garage (車庫に入ります) after this scene, then why does it have to choose an obsolete railway? (BTW, 使い捨て is usually disposable or single-use, but I think obsolete is fine here.)
A rather literal translation would be "(There are) distorted and obsolete railways running side by side". 歪み is the continuous form of 歪む and it safely modifies レール in combination of 並ぶ. As I mentioned in the other question, I guess these four lines describe a passing loop where local trains avoid (避ける) faster trains.
Possible interpretations are 1) someone saw the local train, the signal light, the switch and the obsolete railroads from inside the express train, or 2) this scene is depicted totally from the third-person objective viewpoint. I prefer the latter; I see very little intention or will throughout the lyrics, and I don't want to use the first-person viewpoint (i.e., "I" or "we") too much. I feel it's better to translate the song as if you were a transparent portrait painter or a ghost camera operator.