Pavement Performance Measures and Forecasting and The Effects of Maintenance and Rehabilitation Strategy on Treatment Effectiveness (Revised)

CHAPTER 1. INTRODUCTION

This final report of the study entitled Pavement Performance Measures and Forecasting and the Effects of Maintenance and Rehabilitation Strategy on Treatment Effectiveness presents the findings and recommendations of the research team. The study was based on the following three groups of objectives:

• Group A—Condition State (CS): Address the classification of the CS (good, fair, or poor) of the various pavement segments and types based on their identified and measured functional condition (ride quality and safety) and structural integrity (rut depth and cracking) and their rates of deterioration.
  
  
• Group B—Treatment Effectiveness: Address the developed methodology used to estimate the effectiveness of each pavement treatment type and combinations of treatments based on the time-series pavement condition and distress data. The series of pavement maintenance and rehabilitation treatments required to improve the longevity of the pavement structures and hence the pavement lifecycle costs were evaluated.
  
  
• Group C—Roles of Pavement Treatments: Document the roles of pavement maintenance and rehabilitation treatments in the design of long-life pavements through quantification of the pavement RFP and RSP.

Analyses of the pavement conditions, distresses, and other data were conducted to support each objective group. The data used in the analyses were obtained from Standard Data Release 28.0 of the LTPP database published in January 2014 and from three State transportation departments—CDOT, LADOTD, and WSDOT. The data for all LTPP treatment types performed on test sections within the Specific Pavement Studies (SPS) (SPS-1 through -7) and General Pavement Studies (GPS) (GPS-6, -7, and -9) experiments were downloaded and organized for analyses. For some treatments, the before-treatment and the after-treatment pavement condition and distress data of each test section were modeled and analyzed to do the following:

• Determine the treatment benefits.
• Assess the impacts of the applied treatment strategies on the pavement performance.

The study objectives were formulated to perform analyses and make recommendations in support of objectives 7 and 9 of the Long-Term Pavement Performance (LTTP) Data Analysis Program—Expanded Strategic Plan.⁽¹⁾ The following specific LTPP goals and objectives were addressed and accomplished in this study:

• Performance measures of various distress indicators for different pavement types were established. The measures were used to develop pavement condition classification systems based on good, fair, and poor ratings.
  
  
• Efficient pavement performance prediction methodologies for pavement maintenance and rehabilitation options were developed to characterize series of pavement maintenance and rehabilitation activities applied over the life of a pavement system. Recommendations for incorporating the methodologies into subsequent studies on maintenance and rehabilitation timing and strategy selection were also made.
  
  
• The roles of pavement preservation/maintenance and rehabilitation in the design of long-life pavement and quantification of the remaining service life (RSL) of cracked or damaged pavements were addressed.

During the study, pavement condition and distress data and other inventory and treatment data from the LTPP experiments and from three State transportation departments (CDOT, LADOTD, and WSDOT) were obtained, organized, and analyzed to do the following:

• Define the pavement performance in a way that supports the selection of cost-effective pavement treatment strategy.
  
  
• Provide better estimates of pavement treatment effectiveness and the role of pavement treatments in the pavement’s service lifecycle.
  
  
• Develop pavement performance prediction methodologies applicable to the pavement condition and distress data collected before and after the application of treatments or series of treatments.
  
  
• Analyze whether FWD data could be used to indicate impending surface defects.
  
  
• Make appropriate recommendations for subsequent studies regarding the impacts and/or selection of pavement maintenance, preservation, and rehabilitation options and strategies and their impacts on the pavement service life.

Consequently, the contents of this final report are organized in the following nine chapters:

• Chapter 1. Introduction: This chapter describes the objectives of the study and outlines the contents of the report.
  
  
• Chapter 2. Literature Review: This chapter includes a detailed literature review conducted in support of phases I and II of the study. The literature review addresses the state of the practice of various State transportation departments and the methodologies used in their analyses and interpretations of the pavement performance data. This chapter also provides a detailed review of previous analyses of the LTPP data and their consequent findings and recommendations as they relate to this study.
  
  
• Chapter 3. Pavement Condition Classification: This chapter presents the newly developed dual pavement condition rating systems.
  
  
• Chapter 4. Data Mining and Synthesis: This chapter summarizes the number of LTPP test sections and the number of applied treatments for which the LTPP database has sufficient time-series data to conduct the analyses in phase II.
  
  
• Chapter 5. LTPP Data Analyses of Flexible Pavements: This chapter summarizes the results of the analyses of the LTPP flexible pavement data.
  
  
• Chapter 6. LTPP Data Analyses of Rigid Pavements: This chapter summarizes the results of the analyses of the LTPP rigid pavement data.
  
  
• Chapter 7. FWD Deflection Data Analyses: This chapter summarizes the results of the analyses of the LTPP deflection data
  
  
• Chapter 8. State Data Analyses: This chapter details and discusses the methodologies used in the analyses and the results of the analyses of the pavement performance data obtained from three State transportation departments—CDOT, LADOTD, and WSDOT.
  
  
• Chapter 9. Summary, Conclusions, and Recommendations: This chapter summarizes the report, presents the conclusions, and makes recommendations regarding practices going forward as well as suggestions for future studies.

Readers should note detailed data and results from this study are available through LTPP Customer Support Services by telephone at (202) 493–3035 or by email at ltppinfo@fhwa.dot.gov.