Projects can be a collection of numerous interdependent subsystems, including activities, resources, information, etc. Complexity has been found to significantly impact the realisation of projects in terms of scope, time, and cost, and hence influences the discipline of project management. Studies confirm that most megaprojects do not meet their defined scope, time, and cost estimations and hence can be considered project failures. Despite many research studies considering these issues, projects still fail. This has been primarily due to a poor understanding of complexity, particularly the non-linear and dynamic interactions and interdependencies between project elements and the project and its surrounding environment. These issues can lead to deviations from defined objectives, delays, and cost overruns. Nonlinearity in complex projects causes unpredictability in the relationship between inputs and outputs. The behaviour of nonlinear systems can, on occasion, be predicted by employing some qualitative patterns, but complex systems are generally not responsive to conventional systems analysis. As modern projects are becoming more complex, new types of management approaches for projects are needed. Research is therefore needed to both: (i) understand complex issues within projects and (ii) decide how to manage complexity appropriately. Railway infrastructure projects are particularly vulnerable to disruptive events caused by uncertainties and internal and external influences (such as scope change, change in design etc.) during their lifecycle. The adaptive capacity of systems refers to either the ability of the system to (i) return to its equilibrium point when disruption is encountered, using its programmed strategies, and planning methods, or (ii) adopt new approaches to respond to events that are outside of its preconfigured design and structure. The measure of the rapidness of a project to recover from disruption is referred to as resilience. The literature review highlighted a few of future research avenues to achieve a reliable tool to assess project resilience : (i) apply methods in more advanced fields (i.e. applicable to megaprojects); (ii) identify a set of validated indicators that can assess a project's resilience, and hence its ability to manage disruptions; (iii) conduct structured experimental studies based on identified indicators that can evaluate proposed conceptual frameworks for assessing project resilience, and (iv) develop tools to be used by project stakeholders and managers to evaluate the impact of efforts required to enhance the resilience of the existing and future projects. Such a tool could be applied to measure a project's strengths and weaknesses and suggest action plans to improve its resilience. The tool would augment existing project risk management strategies and hence help projects to become more resilient when facing disruptive events or unexpected changes. The scope of the research is to develop and apply an innovative methodology and analysis tool to railway project management. The approach considers project management as a system and utilises concepts and methods of system dynamics, to model the system (and its subsystems) and to evaluate its resilience. To evaluate the real-life application of the proposed method, the author applied his proposed method to measure the resilience of metro systems in response to disruptions or additional operating hours. The results are presented in Chapter 8. The research aims to propose an innovative systematic, and reliable methodology to consider railway project management structure as a complex system and model its subsystems via Causal Loop Diagrams. To do so, the following objectives are defined: • Generate a set of systematically developed causal loop diagrams for key subsystems of project management and conduct qualitative analysis to identify the resilience factors of each subsystem. • Integrate and synthesise the modelled subsystems through developing innovative structured and formulated stock and flow diagrams (SFD) and studying the resilience of the proposed schematic project management structure. Qualitative analysis will be utilised to study interactions between developed subsystems • Convert and propose the developed SFD into an innovative modelling tool, which can be adapted to any railway project and enable users to analyse trade-offs between different variables affecting project management resilience, as well as evaluate the impact of decisions on project performance. • Develop a set of novel and unique CLDs and SFDs to model metro system operation management environment and analyse its resilience to be converted into 24-hour metro operation. The proposed approach and platform of thinking are proposed to be applied as a complementary tool to measure the resilience of project management for railway infrastructure schemes and to add value to the existing project risk management approaches. Project management was considered as a system with five main subsystems, namely, project governance, requirements management, configuration management, in-house engineering and change management. Multiple case study analysis was used to diagnose and identify the main components of the proposed subsystems that most affect the vulnerability and resilience of the system the most. To achieve this, questionnaires were designed to survey the key components and factors, to be finally used as the main variables for generating causal loop diagrams for each subsystem. Then CLDs were quantified to facilitate quantitative analysis in addition to the qualitative analysis. The full methodology is presented in Figure 1.5. This thesis presents an innovative combination of qualitative and quantitative analysis approaches founded on system dynamics tools, to evaluate the resilience of the proposed schematic project management structure for railway. The main idea was to propose an innovative and practical approach to applying system thinking to conventional project management strategies to reinforce it and bridge the existing gaps to manage the growing complexity of modern projects., as highly recommended by previous researchers. The proposed schematic project management structure and subsystems are modelled using the data derived from multiple case study analysis, causal loop diagrams (CLDs), and Vensim software. Generated CLDs were reviewed by a group of external experts and some from the studied projects to validate the realism of the CLDs. CLDs are simplified systematically to keep the reliability and at the same time applicability for analysis. CLDs provide a set of cross-validation tools such as the Uses tree and Cause tree, which deliver traceability features of the generated CLDs. Uses trees can be used to trace the impact of any selected variable on the other components of the system., whilst the "Cause Tree" can be used to figure out the variables with an impact on any selected component. Employing these tools, provided a reliable qualitative analysis tool and allowed the author to bring out the causal feedback of each CLD and identify the key resilience indicators for each subsystem of the model (Qualitative analysis). The qualitative analysis of CLDs highlighted the key resilience indicators affecting each subsystem and reflected the causal feedback of the loops. The traceability feature of the CLDs can be adopted as an applicable method to simulate the environment of complex projects and assist managers to visually trace the impact of their decisions on the performance of the project. The research contribution can be briefly summarised as: • Developed and proposed an innovative methodology combining multiple case study analysis and system dynamics tools, which can be followed by future researchers to visualise the complex environment of projects. • Generated a set of reference CLDs to model the railway project management as a system. These models are developed for the first time and deliver a holistic overview of any similar railway project. Researchers can adapt these reference models and map their individual systems against the generated CLDs. Hence, the CLDs can be modified to reflect the true nature of any specific system (Qualitative analysis tool for complex railway projects). • Designed, formulated, and proposed a novel SFD to analyse the resilience of the railway's proposed schematic project management structure, according to the resilience indicators identified via CLD analysis. The author designed a unique user interface for system analysis. This is the first-of-a-kind toolset, which allows managers and researchers to change the resilience indicators of the project management and analyse its impact on project performance and management resilience (A novel quantitative analysis tool applicable to all railway projects). • Based on the findings from qualitative and quantitative analysis, the author developed a set of novel formulas and a conceptual two-dimensional model to enhance the understanding of project resilience. This creates a platform of thinking and proposes new research avenues for future researchers to focus on other dimensions with potential impact on resilience and achieve the optimum level of performance. • Designed and proposed a unique system dynamic tool, formulated, and structured to assist managers and planners to analyse the resilience of metro operation environments. The tools can be sued to manage disruption in the metro system or in the case of converting metros to 24-hour metro operation and analyse its impact on metro system resilience.