The driver of the coach bus deviates from his lane due to the actions of Balthasar Boma. This deviation is shown from the outside. It is clear that the bus is on a closed route: an intersection can be seen in the background. The lane on which the bus travels is closed at that intersection with approaching gates. There are no other side streets between those gates and the bus. Logically, this means the bus could only be at that point via the intersection.