Do you know where to go?

[Silverobama]

I was on my way to place B and I saw a foreigner in the subway station. He was looking at where the train goes and I thought he must need some help. Then I went up to him and asked him:

Do you know where to go?

Is this italic sentence natural?

 

[BobK]

That doesn't sound natural; it's grammatical, but would be appropiate in a totally different context (where you are the one needing information: Do you know where to go to buy apples at this time of day?. A good alternative for what you want to say would be 'Where are you trying to get to?', or just 'Can I help?'

 

[Rover_KE]

I hear 'Can I help you?' more than anything else.

 

[emsr2d2]

I was on my way to place B and somewhere when I saw a foreigner in the subway station. He was looking at where the train goes the subway map/the timetable/the electronic signs and I thought he must need some help. Then I went up to him and asked him:

Do you know where to go?

Is this italic sentence natural?

Note my changes above. I don't find that natural at all. I'd use something like the following:

Do you need some help?
Where are you trying to get to?
Are you OK there? Can I do anything useful?