I’m looking at the SBB app to look at train times between Luzern & Mürren & Luzern & Wengen in mid April. The app tells me of construction and the need for taking replacement buses and that the train/ bus connection is “guaranteed” at Interlaken West. I don’t understand what all this means. So I don’t change trains in Interlaken Ost? How would I get to Mürren or Wengen? I may go to both on two different days. How long is the bus ride? What am I supposed to do?