Sound effect らん with unknowing meaning, and meaning of pun 裂けて　避けた


So I was translating a song (full lyrics here:
[反芻の印象](http://vocaloidlyrics.wikia.com/wiki/%E5%8F%8D%E8%8A%BB%E3%81%AE%E5%8D%B0%E8%B1%A1_\(Hansuu_no_Inshou\)))
and there is an onomatopoeia in the middle which I don't understand. It's らん.
It repeats multiple times (you can hear it in the song on Youtube,
[【初音ミク】反芻の印象【オリジナル曲】](https://www.youtube.com/watch?v=M8nWZSiQd48), at
[1:00](https://youtu.be/M8nWZSiQd48?t=59s)) and I don't know what it's trying
to mimic. I can't find what it could mean anywhere, and I don't know what it
could be besides that. The song is about trains, so I'm assuming the sound
effect is related to that, but really I have no idea what it's supposed to
sound like, even after listening to it over and over.

Additionally, the line after that in the song is:

> 裂けて 避けた

(I tore it up and avoided it?) which I'm quite sure is a pun, which is why I'm
hesitant to translate it as written, especially since it doesn't really make
contextual sense. (As the next lyric is 鈍行列車 点いて 消える きまぐれ信号, the slow train
lights up (the night) and then vanishes, a whimsical signal - that makes sense
together, but not with 裂けて 避けた.) Is this just a weird line, or is there some
meaning to these words, especially put together, that I'm not seeing?

Thank you for your help!




The somewhat monotonous tone of this らん reminds me of the sound of Japanese
[踏切 (railway crossing)](https://youtu.be/roQX6xtuvIw) since this is a song
about trains, but its sound is usually カンカン. I'm not sure if it's really
related. らんらん, ラララ, ルルル and so on are often used as a meaningless phrase in
songs, so it can be simply meaningless. ([遠い日々](https://youtu.be/V9d-1XuqGCM)
from _Nausicaä of the Valley of the Wind_ is a famous song which only says
らんらん.)

As for the "裂けて 避けた" line, I think it's a relative clause that modifies 鈍行列車.
Please notice nouns come _after_ the corresponding verbs on each line of that
stanza. 鈍行列車 is a local train as opposed to express ones. So the literal
translation would be "A local train which was torn and avoided". I'm not 100%
sure, but my best guess is that this refers to [a passing
loop](https://en.wikipedia.org/wiki/Passing_loop) (or
[待避線](https://ja.wikipedia.org/wiki/%E5%BE%85%E9%81%BF%E9%A7%85) in Japanese),
where a railroad is "torn" (branched) and express trains "avoid" local trains.
The following three lines seem to be also about a passing loop or a siding
(signal light, railway switch, curved and aligned railroads). 使い捨て is "single-
use" or "disposable", but here it seems to refer to an old siding which is
rarely used.

