What does the 月 (moon/month) in the Taiwanese MRT platform's 月台 refer to? On a recent trip to Taiwan, I noticed that the MRT platforms there are labelled 月台 (yuetai / yuètái). Asking a professional tour guide (Taiwanese local, native Chinese speaker) only revealed that he'd never been asked that question, but he didn't have an answer for me.

Googling around, I found the following synonym: zhàntái ( 站台 ) - Han trainer dictionary, which sounds more understandable (platform for standing). However, I don't see any connection between MRT platforms and months or moons. There doesn't seem to even be a link to shape, as the platforms are straight. (The 'queue-up' lines drawn on the ground are often L-shaped - that's closer to a moon shape.)

Here are some links to photos containing the phrase:


Taipei MRT rolling stock at Platform 2, Ximen Station 20080317.jpg
MRT Taipei Main Station Platform 1 20070503.jpg
Taipei Taiwan MRT-Station-Ximen-01.jpg


My question: What does 月 refer to in the Taiwanese phrase for MRT platform, 月台?
None of the references is very authoritative, but all of the search results agree with each other, that 月台 for 'railway platform' is an extended meaning from its original meaning 'moon-watching balcony' which refers to a platform that protrudes from a building.

月台 （建筑样式） 编辑 讨论
在古时建筑上，正房、正殿突出连着前阶的平台叫“月台”，月台是该建筑物的基础，也是它的组成部分。由于此类平台宽敞而通透，一般前无遮拦，故是看月亮的好地方，也就成了赏月之台。而现代的月台通常指进入火车站后方便旅客上火车的一段与火车车门踏步平行的平台。

https://baike.baidu.com/item/%E6%9C%88%E5%8F%B0/871716

https://www.guokr.com/question/543681/

https://www.rrb.gov.tw/07211.aspx?id=652

https://www.zhihu.com/question/29310884