We try to discover this relationship by applying to the
data some heuristics and trajectory cluster algorithms. In the
following the extraction process for estimating bus stops is
shown in detail:
Trajectory segmentation. We divide each bus trajectory into
segments, by means of a heuristics that splits a trajectory
whenever the time gap between two consecutive
points exceeds a given threshold. Therefore, each
resulting segment represents a trip of the bus on a
line. A sample illustration of the effects of this step
is shown in Figure 1, where a single bus trajectory
actually corresponds to four different routes, served
by the same bus at different times