LIST OF EQUATIONS
1. Chapter 1 Introduction
1.7. Thesis Structure
This thesis has 11 chapters plus references and appendices. The structure is as follows:
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Chapter 1: Introduction. This chapter has introduced the need for a thorough understanding of the background information of the research. It also explains the motivation for the study and identifies the research problem, aim, objectives and research significance. The final section of this chapter provides an overview of the structure of this thesis.
Chapter 2: Impact of Climate Change on Pavement Resilience (Literature Review-Part 1). This chapter provides a review of the literature relevant to pavement infrastructure. It starts with a thorough examination of pavement performance that covers types of pavement performance indicators and pavement deterioration modelling theory relevant to this research, and the association between climate change and pavement failure. It also describes the existing literature about the Markov chain and system dynamics. Infrastructure resilience and measuring infrastructure resilience are also covered.
Chapter 3: Theoretical Method for Modelling Pavement Deterioration (Literature Review-Part 2). This chapter focuses on the climate change model, its impacts on road pavement structure and the measurement of impacts associated with future climate prediction. The chapter is also targeted at identifying the existing state of knowledge concerning pavement temperature, and the Thornthwaite Moisture Index in the United Arab Emirates (UAE). Defining pavement deterministic and probabilistic modelling with respect to the Pavement Condition Index (PCI) and the total change in roughness is also studied in more detail. Chapter 4 is a platform for building a theoretical background for the modelling of a pavement deterioration model. Total change in roughness is built from different elements: rutting component, cracking component and environmental component. The HDM-4 model is used to build new determination modelling with respect to the impact of climate change.
Other models such as Markov chain model, pavement temperature and Thornthwaite Moisture Index are also determined. Measuring resilience is also studied.
Chapter 4: Methodology. The methodology of this research is focused on presenting a roadmap for the study. A detailed framework including all tasks is described, including the development of data sets, developing a deterministic model for pavement deterioration, determining the deterioration mode using the Markov chain method, determining the deterioration mode using the system dynamics method
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and the concept of measuring the pavement resilience and investigation of climate change.
Chapter 5: Data Collection and Analysis. This chapter explains the research data collection and analysis approach used to conduct the study. it examines the types of data and sources including International Roughness Index (IRI), asphalt surfacing rutting and cracking, traffic data, heavy vehicle speed (sh), asphalt surfacing thickness (Hs), asphaltic ageing and UAE weather data. This chapter represents a description of how the development of research model inputs is designed, such as development of predicted maximum air temperature (Tmax) in the UAE and pavement temperature (TPmax), predicted Thornthwaite Moisture Index (TMI) in the UAE, binder softening point (SP) and voids in mix (VIM). Information on questionnaires is also addressed.
This chapter concludes with a description of the statistical methods that are used in the analysis, confidentiality issues and compliance with ethics. A summary of the variable inputs is finally drawn.
Chapter 6: Developing Pavement Deterioration Indicators. The methodology selected to develop the model was described in Chapter 2 and data collection and analysis was discussed in Chapter 5. This chapter’s goal is to estimate the pavement deterioration indicators that later will be used as parameters and inputs that shape the models in chapters 7, 8 and 9. Such indexes are built through the deterministic model concerning different climate change scenarios. The chapter explains the process used in the development of the model inputs using obtained analysed data discussed in Chapter 5. The chapter also provides details on the computation of the change in total roughness based on default HDM-4 equations.
Developing new equations and coefficients is also investigated. Testing and comparison of the results are presented. Finally, the relationship between International Roughness Index and Pavement Condition Index is also investigated.
Chapter 7: Forecasting Pavement Deterioration using a Markov Chain Method. This chapter’s goal is to build the pavement deterioration model using a Markov chain with parameters developed in chapters 5 and 6. The model in this chapter is formed from two main elements, transition probability matrix and pavement condition rating. There are different methods for developing a transition probability matrix, as was highlighted in Chapter 4. The chapter explains the process of
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developing model inputs using computed analysed data which was discussed in Chapter 6 with different climate change scenarios for years 2013, 2020, 2040 and 2060. Finally, the chapter introduces pavement deterioration curves based on PCI and IRI with different climate change scenarios.
Chapter 8: Causal Loop Diagrams for the Pavement Deterioration Model.
The purpose of this chapter is to forecast the pavement deterioration using system dynamics based on the established parameters from Chapter 6. The chapter investigates the impact of the pavement deterioration model with respect to generic risks that were developed in Chapter 3.The interdependencies between pavement failure risks due to climate change and pavement deterioration constructs were established by causal loop diagrams. These causal loop diagrams were used in the SD models as discussed in Chapter 9.
Chapter 9: Modelling Pavement Deterioration Using System Dynamics.
Developing an understanding of risks associated with road pavement failure (pavement deterioration) was achieved and the risks were used as inputs into the system dynamics models as discussed in Chapter 8. This chapter explains the methodology adopted in the use of Stock and Flow modelling in system dynamics.
Deterministic risk analysis is explained in this chapter. Vensim software was used to run the proposed model. Then, knowledge obtained on the risks related to pavement failure (pavement deterioration) will improve the success of the computational model through defining all the elements that could contribute to the change in IRI value and subsequently to PCI. Such an approach was developed from the stock and flow diagram to enrich the system in order to establish the dynamic behaviour for the selected variables. The pavement deterioration curve was introduced regarding pavement performance indicators PCI and IR with different risk scenarios. The chapter finally presents and discusses the results from the different modelling exercises.
Chapter 10: Measuring Resilience Loss. This chapter’s goal is to measure resilience loss for pavement networks. The pavement deterioration model using Markov chain and system dynamics with parameters developed in chapters 5 and 6 is used to determine the resilience loss. The model in this chapter is formed from two main elements, measuring the main performance by integrating the area under the
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survival curves and measuring resilience performance with respect to 100% perforce functionality of the pavement network. The chapter explains the process of development of resilience loss using a Markov chain model with different climate change scenarios for years 2013, 2020, 2040 and 2060. Also, a system dynamics model with different risks associated with climate change is developed. Comparison of the results between the two models is finally reported.
Chapter 11: Discussion and Conclusion. This chapter represents a comprehensive discussion of the findings and provides a clear picture about the relationships among the study variables, the degree to which the obtained results agree with or differ from the past empirical outcomes, and theoretical arguments. This chapter also presents a discussion of the key research objectives and themes analysed throughout this thesis. The first section presents a discussion on the findings of the eight objectives. This is followed by a discussion on the strengths of the research methodology and validation and implication. The last section presents the conclusion of the thesis covering the limitations of the research, summary of contributions, and future research and recommendations. This is achieved through discussing the main concepts of the research including the concepts of measuring pavement resilience and developing a pavement deterioration model using system dynamics and Markov chain.
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