We had a nice few days in Düsseldorf and Cologne this week and I will do a trip report later but I thought it was worth warning people that things can go wrong with the trains. I bought our ticket back to Düsseldorf airport from Cologne well in advance as the lines at the ticket office are very very long and the automatic dispenser is a bit hard if you don't speak the language (although there did seem to be someone on hand to help). Our problem was that the 17.49 train to the airport (just a 30 minute journey) was delayed by an hour. The line to ask someone advise was about 30 or 40 deep so we just picked another train from a very complicated looking time table that we could see was definitely going to the airport but it took an hour 20 minutes. . What we should have done was get the times of other trains around that time so that we would have an alternative in an emergency.