A quick and dirty analysis was made of all business trips at ROB up till now in 2019, and in particular, which transport (plane, train, car, etc) was chosen.  In most cases, this is pretty obvious: everyone going to Paris has taken the Thalys and everybody going to the US has taken the plane. There are destinations however, for which it is your choice that makes the difference. Roughly half of the people go by car to Noordwijk, the other half takes the train. The same for Darmstadt. In other cases, people had to choice between train and plane and choose for the first option when travelling to destinations like Toulouse, Marseille, Gottingen or Bern. Sure this takes the better part of a day on the train, but it is way more ecological and you can work on the train. If your colleagues have chosen this option, maybe it is worth considering?