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3.2 Issues in the Proposed Crew Rescheduling Approach
This section presents issues related to the proposed crew rescheduling approach and discusses its details. The first issue concerns the crew schedule rescheduling approach
or crew rescheduling approach. Both approaches have different concepts and complexities. The second issue pertains to whether to propose a complete crew
scheduling system or make an addition to the current system. The complete system comprises finding optimum crew schedules plus an automated crew-rescheduling
module while an additional system consists only of a crew-rescheduling module.
3.2.1 Crew Schedule Rescheduling versus Crew Rescheduling
In bus crew scheduling problem there are two ways of rescheduling: one is to reschedule the schedule itself and the second is to reschedule the peoplecrewdriver
Kwan, 2004. Crew schedule rescheduling is whenever disruption or UE occurs, the
affected crew schedule will be rescheduled. However, crew rescheduling means if any
disruption takes place, the crew schedule will remain the same but affected crewsdrivers will be rescheduled or reassigned. For example, Crew A is late for
morning shift. If we use the crew schedule rescheduling approach, then the crew schedules will be changed accordingly. In the
crew rescheduling approach, the crew schedule is still the same, but other available crew or spare crew has to take over A’s
duty. Huisman and Wagelmans 2006 have proposed the crew schedule rescheduling
approach for whenever a bus is late. Yet, in this research, we propose using the crew
rescheduling approach because of the complexity associated with crew schedule rescheduling. This could be understood from the constraints i.e. driving hour rules of
the crew itself. When trying to conduct any rescheduling activities, schedulers need to consider cost and time factors, such as number of available members, driving hours left
for each one, and the location of every crew. With such added constraints, it becomes very difficult for the system to find an optimum schedule. One of the assumptions of
Huisman and Wagelmans 2006 is the availability of unlimited crew members. However, this is not realistic. In realistic situations, it is not practical to reschedule the
crew schedules whenever a crew becomes unavailable because this may change driving hours or break timings and assigned routes, in addition to the time it takes to do that. In
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this research, the crew rescheduling approach will be explored in an attempt to tackle
the problems of UE related to crew members based on realistic situations.
3.2.2 Complete System versus Additional System
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