Incorporating Pavement Sustainability into Municiple Best Practices
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Maintaining a functioning road network is a challenge in today’s society due to the financial restrictions faced by all levels of government. A means of determining how to efficiently spend their limited funding must be found. In addition, the concept of sustainable development is rapidly growing in today’s world pressuring municipalities towards operating in a more socially and environmentally friendly manner. Sustainability is broken down into three aspects which are economical, social and environmental. A truly sustainable pavement satisfies its functional requirements while aiding social and economic development and minimizing negative environmental impacts In response to the growing sustainability trend, the City of Markham is committed to incorporating sustainability into their daily operations. This thesis is the result of a research project with the City of Markham which is directed at incorporating sustainable practices into pavement engineering. The objective of this project is to provide a practical framework for incorporating pavement sustainability best practices into the pavement engineering operations at the City of Markham. This practical framework is developed through the completion of four primary objectives. The first main objective involves the completion of a comprehensive literature review that identifies and reviews the state-of-the-art sustainable pavement best practices. This literature review is divided into five pavement related categories which examine: materials, design and construction techniques, maintenance and rehabilitation techniques, sustainability evaluation systems and carbon footprinting. The second objective involves the quantification of the environmental, economic and carbon footprint impacts of the reviewed pavement best practices; this evaluation is conducted using PaLATE. PaLATE is an excel based software developed at the University of California for evaluating the economical and environmental impacts of various pavement technologies. The third objective involves the utilization of GreenPave for evaluating the environmental friendliness of the analysed pavement best practices. The green discounted life cycle cost (GDLCC) is calculated to include the economic aspect of sustainability. The final objective involves the development of project and network level frameworks. These two frameworks are connected which forms the final framework for incorporating sustainability into City of Markham’s pavement engineering operations. Guidelines for the proper utilization of the developed framework are provided. Through the completion of the literature review it is concluded that there is a wide variety of sustainable pavement technologies that range from project design to pavement decommission. PaLATE analysis results indicate that warm mix asphalt and full depth reclamation are the most environmentally friendly construction and rehabilitation techniques, respectively. Including recycled asphalt pavement (RAP) within pavement mix designs reduces both costs and environmental impacts. Excluding microsurfacing, full depth reclamation was the least expensive rehabilitation technique while hot mix asphalt with RAP was the cheapest construction technique. The same initial construction and rehabilitation techniques are evaluated using the GreenPave rating system. Pervious concrete scored the highest rating under the initial construction category with warm mix asphalt a close second. Cold in place recycling, cold in place with expanded asphalt and full depth reclamation all scored the highest under the rehabilitation category. In the future, the City of Markham may wish to alter the GreenPave rating system to be more reflective of municipal practices as the current version of GreenPave is weighted more heavily on high volume roads. To include the economical aspect, the green discounted life cycle cost (GDLCC) is calculated for all techniques. Hot mix asphalt with RAP and full depth reclamation resulted with the lowest GDLCC in the construction and rehabilitation categories, respectively. Finally, the recommended project and network level frameworks for incorporating sustainability into the pavement engineering practices at the City of Markham are proposed. On the project level, GreenPave evaluation and project level GDLCC aid decision makers in determining the most sustainable project alternative. On the network level, a pavement management system (PMS) serves as the platform. The role of a PMS is to provide recommendations on when and where rehabilitation is required and which rehabilitation technique is the most sustainable. The cost effectiveness and network level GDLCC indicators also aid pavement engineers in making network level decisions. The project and network level frameworks are connected to provide a complete pavement management framework for incorporating sustainability. The framework provides economic benefits by increasing the effectiveness of budget allocation; this is accomplished by maximizing the overall condition index gained to dollar spent ratio. The environmental benefits of this framework include the minimization of harmful gas emissions, project carbon footprints and energy and water consumption. The social issues of pavement projects are unique to each case and therefore must be addressed case by case. A common starting point when addressing these issues is provided.