Why does my bus/tram not always depart exactly at the time listed in the timetable?

We strive as much as possible to travel exactly on time. Unfortunately, we cannot guarantee exact departure times. However, our drivers are instructed to always depart on time at the very first stop for a route. 

Approximate times only, actual times may vary.

We cannot guarantee exact times because traffic does not always allow this to occur. A tram/bus may arrive somewhat earlier or later at a stop due to how busy the traffic is, disruptions on the route, and may even arrive early if there is little traffic on the route. The arrival and departure times may deviate somewhat from the times on the departure overview at the stop. This is indicated on the departure overview by the text "Times are approximate, subject to change."