So I was listening to a short japanese lesson and it came out a situation where you’d need to know the direction of the train you’re taking, in order to make sure it’s the right one.
The sentence in english would be, for example: “Is this (train) headed to Tokyo?”
The japanese translation they gave is: “東京行き(ゆき）ですか”
To me that’s totally fine, but before listening to that sentence, I thought I could say “東京まで行き(ゆき）ですか” in order to specify the direction, even if it would be already set by the 行き part (?).
Is my sentence still correct (maybe more formal?) or is just an unnecessary “specification”?
行き is a suffix, so it has to attach to the place name directly. You could ask 東京までですか if you wanted to know if something goes to Tokyo using まで. It’s just more that you’re asking how far it goes rather than the direction in that case, so if you don’t know the direction, it would be a little weird.
