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when dealing with a large number of resources and demands, they require a long time to find optimum allocation Rzevski, 2002. Whenever resources or demands change,
these programs start the allocation process from the beginning and if changes are frequent, they oscillate and cannot reach the optimum solution.
The main characteristic for a tool that we are looking for is the ability to find quick solutions in real-time whenever UE take place and in an uncertain environment. The
capabilities of a MAS, especially when dealing with changes in real-time and in uncertain environment, matched our requirements Weiss, 1999; Shen et al., 2001;
Wooldridge, 2002. To the best of our knowledge, the application of a MAS to bus crew scheduling problem is a novel idea. Thus, in this research we propose using a MAS as a
tool to automate the crew rescheduling process. Details of a MAS are discussed in Chapter Two.
1.3 Research Aim
and Objectives
The research carried out in this dissertation is based on the stance that current approaches do not provide solutions to automate the crew rescheduling process and help
supervisors in dealing with UE so that the effects can be minimised. The aim of this research therefore is to develop an automated crew rescheduling system using a MAS to
assist supervisors in managing UE. By doing so, it should minimise the effect of UE on crew schedules and hence reduce the amount of disruption to bus operation. To achieve
the research aim some suggested objectives are summarised as follows: 1. The first objective is to review and critically examine the existing approaches in
producing crew schedules and whether they have any mechanisms for tackling UE. The reason for this is to learn from current approaches if they have a
mechanism for dealing with UE problems and to know its efficiency. 2. The second objective is to understand the nature of UE, the causes of UE, and
how bus operatorcompanies deal with UE. This is in order to understand UE in detail and the manual way of managing UE to model them before automating
the process, especially crew rescheduling.
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3. The third objective is to assess whether a MAS can be used to develop the proposed system.
4. The fourth objective is to designdevelop an automated crew rescheduling system. The aim of the automated system is to help supervisors in managing UE
in everyday operation. 5. The fifth objective is to evaluate the proposed system as to whether it achieves
the aim of minimising the problems of manual crew rescheduling and what could be learned from the findings that may improve the proposed system.
1.4 Research Methodology
This section presents the research methodology that used in this research as ways of achieving research objectives. In this research several methods are employed based on
different objectives as outlined below: 1. The literature survey LS is used to obtain information on UE, the sources of
UE, how to deal with UE, current approaches in developing crew schedules and whether the approaches have the ability to deal with UE. Through the LS we
also justify the use of a MAS to implement the proposed system. The LS reviews and analyses the relevant literature in books; theses; working papers;
journal papers; conference proceedings; websites and other academic sources, which are searched by using electronic databases and academic search engines.
2. Interviews are used to gain knowledge of practical experiences of bus companies in managing their daily operation and dealing with UE and how
crews are rescheduled manually. This information helped in modelling the manual way of crews rescheduling.
3. A conceptual model of the proposed automated crew rescheduling system is designed using the MAS concept. AgentPower, a MAS based software package,
is used to develop and simulate the conceptual model.
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4. To evaluate the proposed system, the research carried out two sets of experiments based on a single event and multiple events. The single event
experiment involved testing one event at a time but with different types of events, different types of schedules, different duties distribution and different
event timings. The purpose is of this to test the capability of the proposed system in all types of events and schedules and also to identify the
characteristics of crew schedules that influence the possibility of successful rescheduling. Multiple events test several events that take place concurrently
and randomly. The purpose is to test the robustness of the proposed system in handling many random events at one time. In both experiments, the proposed
system is examined with regard to the research questions, which are elicited in Chapter Two.
5. The experiments’ results are analysed to measure whether the proposed system achieves its aim by looking into its capability of performing quick rescheduling
in real time. The experiments and analysis section will be used to refine the initial hypothesis and revise the initial conceptual approach where appropriate.
1.5 Dissertation Outline
