Dec 28, 2017 - 1:03 AM
in reply to Uallin
Please login to see the attached documents
Platform 31 is probably not as far as it looks. From Platform 6 you just go up the escalator and walk across the bridge and then down into the main concourse and round to Platform 31. There are no Customs or Immigration checks to pass through.
Your planned departure time is probably running into the morning peak but I'm not sure how busy the train to Interlaken will be at that time of year. Check the timetable closer to the time and you will get in indication of how busy the trains will be (denoted by the number of figures next to the train for each class - 3 red figures means chocabloc). See attached example for 9 January.
Looks like your connection from Colmar will give you a 20 minute gap so you should be at platform 31 at least 10 minutes before departure to Interlaken so you should have no problem loading luggage and getting seats. If you are worried the reservations are possible so you might want to consider that or even upgrade to 1st Class to ensure plenty of room for baggage.