The invention relates to a transportation system in an environment comprising several people conveyors as well as a navigation system installed on mobile devices held by the passengers of the transportation system, which transportation system comprises at least one wireless transmission device in connection with at least one of the passenger conveyors, wherein the navigation system comprises a calibration routine for generating a reference position of the mobile device in the environment, and the calibration routine can be initiated, if the distance of the mobile device to the wireless transmission device goes below a threshold value, in which calibration routine the wireless transmission device transfers position and/or identification data to the mobile device, whereupon the navigation system on the mobile device adopts the reference position of the related passenger conveyor.