Dominique Pittenger

Life-Cycle Cost-Based Pavement Preservation Treatment Design

Classic engineering economic theory was developed to furnish the analyst with a tool to compare alternatives on the basis of life-cycle cost (LCC). However, tools used to apply theory to transportation focus on new construction projects with relatively long service lives. These tools do not accurately model the economic aspects of short-lived alternatives such as those that pavement managers must evaluate when seeking the most cost-effective pavement preservation treatment. The field of pavement preservation seeks to “keep good roads good,” and hence pavement preservation treatments are applied to extend the functional service life of the underlying pavement. No significant research has been done to quantify the actual service lives of the pavement preservation treatments themselves nor has a model been furnished to analyze their LCCs. The paper addresses those two gaps in the pavement economics body of knowledge by proposing a methodology for using field test data to quantify the service lives of pavement preservation treatments for both asphalt and concrete pavements. In addition, the paper concludes that an LCC model based on equivalent uniform annual cost, rather than net present value, specifically addresses the relatively short-term nature of pavement preservation treatments and allows the engineer to better relate treatment LCC output to annual maintenance budgets.

Stochastic Life-Cycle Cost Analysis for Pavement Preservation Treatments

The use of life-cycle cost analysis (LCCA) as a decision-making tool in pavement design and the analysis of competing alternatives is recommended by FHWA. However, dependence on deterministic LCCA raises issues about the accuracy of input information because of the degree of construction price volatility found in the underlying commodities used in pavements. Stochastic LCCA has been shown to produce superior results when used at the new pavement design or network level and is suggested for transportation use by FHWA. However, no project-level tools exist to facilitate use of a stochastic approach to evaluate pavement preservation treatment. This paper proposes a practical stochastic LCCA model on the basis of equivalent uniform annual cost, specifically to compare pavement preservation treatment alternatives. The paper explores statistical LCCA techniques that expose inherent uncertainties to identify and quantify the risk of commodity price volatility. The proposed methodology enhances a pavement engineers ability to address budget issues, mitigate risk, and justify pavement preservation treatment decisions. Underlying commodity price volatility in pavement treatment costs can be modeled effectively with stochastic LCCA.

Evaluating Sustainability of Selected Airport Pavement Treatments with Life-Cycle Cost, Raw Material Consumption, and Greenroads Standards

In the global aviation community, sustainability increasingly is becoming a priority for airport projects as a foundation for future prosperity. Pavement structures are an airports greatest asset and greatest liability. Pavement management systems involve an intensive and expensive enterprise, and pavement maintenance projects consume massive amounts of nonrenewable resources at every airport in the nation. Little research has been conducted to assist airport pavement managers in reducing the environmental, economic, and social impacts of pavement maintenance and preservation processes. The old cliché of “what is not measured is not managed” applies, and a performance metric therefore is needed to permit pavement managers to measure sustainability. No standard, quantitative performance metric for sustainability is now in use by pavement managers assessing pavement treatment alternatives. This paper demonstrates how airport pavement managers can quantitatively analyze typical pavement treatments with a life-cycle cost analysis, quantification of raw material consumption, and the recently developed Greenroads standards to measure the environmental, economic, and social impact of the treatments for a given pavement project to enhance the overall sustainability of their programs.

Comparative Analysis of Macrotexture Measurement Tests for Pavement Preservation Treatments

Field pavement preservation research concerning two accepted methods for measuring pavement macrotexture was done on a state highway in Oklahoma. The 2.5-year project used the outflow meter ASTM STP 583 and the Transit New Zealand TNZ T/3 sand circle to measure macrotexture on 23 asphalt and concrete pavement preservation treatments. Through a protocol of monthly macrotexture measurements in the field, the researchers observed functional limitations, caused by the physical mechanics of the methods, on the accuracy of macrotexture measurements on both standard tests. It was found that the sand circle should be used on pavements with macrotexture greater than 0.79 mm (0.03 in.); the outflow meter should be used on pavements with textures of less than 1.26 mm (0.05 in.). Both tests were accurate in the range of 0.79 to 1.26 mm. These results applied to both asphalt and concrete pavements.

Sustainable Pavement Preservation and Maintenance Practices

This chapter discusses the state-of-the-practice in sustainable pavement maintenance and preservation. Its focus is on quantifying and understanding how pavement preservation and maintenance practices minimize environmental impacts. The Federal Highway Administration (FHWA) differentiates between pavement preservation and pavement maintenance and uses this to allocate federal funds accordingly. While Canadian agencies recognize and practice the concepts of pavement preservation, there is no regulatory differentiation between it and maintenance as compared to the US. Pavement preservation promotes environmental sustainability by conserving energy, virgin materials, and reducing greenhouse gases by keeping good roads good. Therefore, a sustainable pavement maintenance program should consider allocating personnel and resources to pavement preservation.

Sustainable Airport Pavements

Sustainability is increasingly becoming a priority issue, as well as the foundation for future prosperity, in the global aviation community. Pavement structures are an airport’s greatest asset and greatest liability, and along with their associated management systems, involve an intensive, expensive enterprise and consume massive amounts of nonrenewable resources at every airport. Pavement sustainability includes assessing various pavement strategies on the basis of eco-nomic, environmental, operational and societal impact throughout the pavement’s life cycle. Getting the most benefit for the least cost is a key attribute of pavement sustainability. This chapter presents an overview of the practices that are funda-mental to sustainable airside pavements, as well as some of the life cycle consid-erations. It includes pavement topics such as pavement condition, treatment types, traffic and climate, as well as life cycle cost, life cycle emissions and energy use and pavement management.

Quantifying the Whole Life Benefit of Preserving Concrete Pavements Using Silicon Reactive Lithium Densifier and Shotblasting – A Promising New Technology

This paper explores the use of lithium based concrete densifier applied over shotblasting as a concrete pavement preservation treatment for locations that are subject to wear due to studded tires, snow chains and snow plowing. The lithium-based treatment was initially developed for anti-scaling and wear resistance properties on concrete pavements to preserve, densify and harden the cement matrix by reacting with the free lime calcium hydroxide to form an insoluble bond calcium silicate hydrate. This study combines laboratory and field tests in California, Delaware, Oklahoma, and Washington, which found that shotblasting the pavement surface and then treating it with the concrete densifier reduces wear/rutting due to abrasion and maintains safe skid numbers for periods of up to 3 years. A stochastic life cycle cost analysis shows this treatment to be a cost effective pavement preservation tool to extend the life of concrete pavements on roads prone to rutting caused by studded snow tires and snow chains. It also finds that the treatment retards the loss of microtexture from aggregate polishing. Finally, the paper does an analysis of the environmental footprint of this form of concrete pavement preservation as compared to current treatment options and finds that the use of lithium based concrete densifier applied over shotblasting is a highly sustainable option for the preservation of concrete pavements in urban areas with significant volumes of traffic.