The suggested answer in English is "That train station is deep yellow" but I would say that "dark yellow" sounds more natural. Not sure if that answer will be accepted also.....
That is true. I think that the colours where you can use deep usually are associated with a real world object that can take a "deep" attribute. Like the deep blue ocean or maybe deep green. That being said, In my lexicon though dark is much more commonly used.
I'd say deep red and dark red are two different colors. A dark red means it's closer to being black, but deep red is a stronger, more vibrant, more pure, less pale red, that also happens to be darker. The difference between the brightness slider and the saturation slider.
I would say using "deep" is acceptable, but with the article "a". For instance, "That train station is a deep yellow." sounds much more natural.
To me, at least, orange is specifically reddish yellow, not just deep yellow. You can have a very pale orange color; it's not necessarily deep at all. If anything, I'd say very deep yellow might become brown, but definitely not orange; the distinction between yellow and orange has nothing to do with deepness.
I suggest including railway station as an option for nha ga. In common use in Australia.
After seeing this sentence more times than I can count, I was curious is such a train station really exists. It does, but it's made out of Legos: http://www.brickshelf.com/gallery/Superb/trainstation/pa244321.jpg