Broadly speaking, the literature concerning the applications of GPS information for improving bus system operations can
be classified into three major areas. First, there is an area of study that utilizes real-time GPS pulses for the design and development
of online control algorithms, management measures and real-time information systems for users and operators. Second,
several studies have proposed to estimate travel time of general traffic by using offline GPS data of buses as probes.
Finally, some studies have used offline GPS data for speed monitoring to evaluate system conditions or improve transit service
by managing schedules or creating timetables.