Pavement Asset Management and Optimization Model: Informing Policy and Enhancing Sustainability
Pavement preservation (maintenance and rehabilitation) requires large resource investments and generates significant environmental impacts. A project-level pavement asset management system (PAMS) including life cycle assessment life cycle cost analysis and life cycle optimization models is developed to determine the optimal pavement preservation strategy. Multi-constraint and multi-objective optimization is conducted to study the impact of agency budget constraints on user costs and total life cycle cost identify the trade-offs between energy consumption and costs and understand the relationships among material consumption traffic congestion and pavement roughness effects. A case study of a hot mixed asphalt (HMA) overlay system shows that a reduction in total agency preservation budget from$2 million to $0.5 million increases the total life cycle cost from $54 million to $61 million over a 20 year service life. A Pareto optimal solution that minimizes energy and cost objectives is also developed to enhance the preservation strategies. The influence of fuel taxes and government subsidies on a PAMS is explored and specific policy recommendations are provided. For example proposals by presidential candidates Clinton and McCain to temporarily suspend the gas tax in the summer of 2008 would have had a detrimental life cycle societal cost impact.
To improve sustainability in pavement design a promising alternative material engineered cementitious composites (ECC) is studied. Dynamic programming optimization technique is applied to minimize total life cycle energy consumption greenhouse gas (GHG) emissions and costs within an analysis period. The results show that the optimal preservation strategies will reduce by 5%-30% the total life cycle energy consumption 4%-40% the GHG emissions and 0.4%-12% the costs for the concrete overlay system the ECC overlay system and the HMA overlay system compared to current Michigan Department of Transportation preservation strategies respectively.