May 27, 2012 - 2:47 PM
If there's no ticket office, there will be a machine at railway stations. And if not, the train personnel will get you a ticket, because it will be the only possibility then. In that case I suppose you will have to tell them before your train departs.
I suggest you take a look at the information about the Swiss Half Fare Card here
, you will also find a link to an overview of the network on which your Half Fare Card is valid (scroll down to see the map) plus information about discounts etc.
I hope this helps. Have a nice trip,