title: Sustainability Evaluation of Road Operational and Maintenance phase: Application of System Dynamics and DPSIR framework
Creators: name: Kaira, Sneha
Publisher: name: Griffith University
Year: 2022
Subjects: subject: road infrastructure
subject: sustainability evaluation frameworks
subject: case studies

description: The Australian Sustainability Development Goals (SDGs) Summit in 2018 attracted much-needed national attention towards environmental goals and targets compared with other aspects of sustainability. Road infrastructure is the backbone of modern society and plays a crucial role in accomplishing a targeted balance between the various aspects of sustainability (economic, environmental, social and governance) and achieving the SDGs. However, a road infrastructure project typically has a long life, and maintaining tangible sustainability outcomes over the development lifecycle remains a daunting task. Moreover, there has been a rise in the severity of multi-faceted impacts on road infrastructure sustainability performance, such as travel patterns, loss of toll revenue, GHG (CO2-eq) emissions and budget constraints (road operation and maintenance costs). Some factors driving such impacts include population growth, climate change and perceptible epidemics like recent COVID-19. To deal with the dynamic nature of such issues and scenarios, there is a need for a framework for assessing a project’s sustainability performance to serve as a decision-making and policy scenario analysis tool. The literature review briefly discusses the significant drawbacks of the available sustainability assessment methodologies. According to the review from Bueno et al. (2015), none of the existing tools includes the requirements to be appropriate for appraising the sustainability of transportation infrastructure projects. The review has further identified the significant prerequisites of a comprehensive sustainability assessment tool, including integrating the broadest possible range of impacts compliant with a lifecycle approach, providing a rigorous method to analyse the balance among the sustainability aspects, and including the context-sensitive nature of sustainability. Thus, to fill the identified research gap, this study identifies an integrated sustainability performance assessment methodology that acts as a decision-making and policy scenario analysis tool. A series of two conceptual modelling techniques—Drivers-Pressure-State-Impact-Response (DPSIR) and System Dynamics (SD)—are employed, with the cause-and-effect relationships of the sustainability indicators developed utilising the DPSIR framework, and the quantitative analysis carried out through a subsequent SD model. The DPSIR helps capture critical factors influencing project sustainability performance through a cause-effect relationship and sets the boundaries of the problem. The SD approach is the preferred method for comprehending the importance of the dynamic perspective of the quadruple bottom line during a SA. The end result of the methodology is the generation of a Sustainability Performance Index (SPI) for road infrastructure during its operation and maintenance phases by analysing the SD model output and DPSIR index layer relationship. Furthermore, the benefits and applicability of the proposed methodology are validated through project case study analysis. Finally, the project’s two alternatives (freeway and toll road options) are analysed in view of the selected case study. As a result, the sustainability performance of freeway and its contribution toward sustainable development is much lower than the toll road from the beginning to the end of the project operation phase. Further, the study introduces three policy scenarios to improve the selected project’s SPI: toll rates, maintenance activities and innovative technologies. In contrast to the base case, it is clear that compared to others, the scenario of combining all three policies has contributed positively to the indicator’s sustainability performance. The results from this scenario indicated that toll standard have increased the government’s financial benefits and rehabilitation work improved the pavement condition decreasing GHG (CO2-eq) emissions from less fuel consumption. Nevertheless, the road user satisfaction with the imposed toll charges affected the traffic volume, further reducing road crashes (by 16.2%), congestion (by 15.5%) and noise emissions (by 0.726 dB ) on the network by the end of the operational phase. In addition, the jobs created are proportional to the road works under maintenance activities and the economic benefits observed are higher under this scenario. It is evident that the research aims to develop a framework to enhance the sustainability deliverables during the project initiation phase and analyse policy scenarios. Thus, fulfilling the research gap of depending and focusing entirely on developing sustainability assessment methods and tools. Moreover, a significant contribution of the proposed methodology is in assessing restricting factors and the effectiveness of the government’s response strategies that influence the long-term achievement of the SDGs.