Pavement Remaining Service Interval Implementation Guidelines

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FOREWORD

Many important decisions are necessary in order to successfully provide and manage a pavement network. At the heart of this process is the prediction of needed future construction events. One approach to providing a single numeric on the condition of a pavement network is the use of pavement remaining service life (RSL). However, many issues exist with the current RSL terminology and resulting numeric that complicate proper interpretation, interagency data exchange, and use. A major source of uncertainty in the current RSL definition is the use of the term "life" to represent multiple points in the pavement construction history. The recommended path to consistency involves adopting terminology of time remaining until a defined construction treatment is required (i.e., RSL is replaced by remaining service interval (RSI)). The term "RSI" has the ability to unify the outcome of different approaches to determine needs by focusing on when and what treatments are needed and the service interruption created. This report provides guidelines for implementing the RSI concept as a replacement to the current remaining life terminology for pavements. The RSI concept is broken down into a series of steps that follow a logical progression. Examples of the concept are presented using pavement engineering methodologies in current use. Suggestions are also provided based on the results of the RSI process. While this report focuses on pavements, it is also applicable to other types of transportation infrastructure. A companion report presents the framework for replacing the current RSL terminology with one based on more exact construction event terms.⁽¹⁾ This report is intended for use by pavement managers and pavement investment decisionmakers across the United States.

Jorge E. Pagán-Ortiz
Director, Office of Infrastructure
Research and Development

Technical Report Documentation Page

SI* (Modern Metric) Conversion Factors

TABLE OF CONTENTS

• EXECUTIVE SUMMARY
• CHAPTER 1. INTRODUCTION
  • BACKGROUND
  • REFORMULATING RSL TERMINOLOGY
  • REPORT ORGANIZATION
• CHAPTER 2. RSI CONCEPT OVERVIEW
  • CONSTRUCTION NEEDS PROCESS
  • CONSTRUCTION EVENT TERMINOLOGY
  • RSI IMPLEMENTATION FRAMEWORK
• CHAPTER 3. IMPLEMENTING THE RSI CONCEPT
  • STEP 1 - SETTING CONSTRUCTION TRIGGERS
  • STEP 2 - SETTING THRESHOLD LIMITS
    • Subjective Approach
    • Engineering Approach
    • Empirical Approach
    • Economic Analysis Approach
    • Combinations Approach
  • STEP 3 - SELECTING OR DEVELOPING EXPECTANCY PERFORMANCE CURVES
    • Models Based on Design Equations
    • Empirical Models
    • Agency Time-Based Rules
  • STEP 4 - IDENTIFYING COLLECTION OF INPUTS
    • Pavement Roughness
    • Pavement Distress
    • Pavement Structural Response
    • Traffic Loads
    • Climate
  • STEP 5 - ESTABLISHING a STRATEGY SELECTION PROCESS
    • Network Analysis
    • Project Analysis
  • STEP 6 - PERFORMING PERIODIC ASSESSMENTS AND UPDATES
    • Assessments
    • Updates
• CHAPTER 4. RSI IMPLEMENTATION EXAMPLES.
  • EXAMPLE 1 - SHA USING PHT ANALYSIS TOOL
    • Background
    • RSI Implementation
  • EXAMPLE 2 - SHA USING THE 1972 AASHTO INTERIM GUIDE FOR DESIGN OF PAVEMENT STRUCTURES
    • Background
    • RSI Implementation
  • EXAMPLE 3 - SHA USING MULTIPLE PERFORMANCE INDICATORS
    • Background
    • RSI Implementation
  • LCC CONSIDERATIONS
• CHAPTER 5. COMMUNICATING RSI FRAMEWORK RESULTS
• APPENDIX. GENERIC AGENCY ISSUES
  • ESTABLISHING AN RSI PROTOCOL
  • IDENTIFYING AND APPOINTING AN RSI COORDINATOR
  • DISSEMINATION OF RSI CONCEPT WITHIN AGENCY
• REFERENCES
• BIBLIOGRAPHY

LIST OF FIGURES

• Figure 1. Flowchart. Future pavement construction needs process
• Figure 2. Flowchart. Agency RSI implementation
• Figure 3. Graph. Conceptual relationship between agency repair costs as a function of pavement condition
• Figure 4. Graph. Three treatment zones as a function of pavement condition
• Figure 5. Graph. Illustrated service histories of trial pavement designs incorporating future overlays
• Figure 6. Graph. Multiple distress-based pavement design where one of the distresses reaches a maximum threshold limit
• Figure 7. Photo. Inertial road profilers used to measure IRI, RN, and other roughness indices
• Figure 8. Photo. FWD used for structural evaluation
• Figure 9. Photo. TSD used for structural evaluation
• Figure 10. Photo. TSD internal pavement response measurement instrumentation
• Figure 11. Photo. WIM sensor used to record truck axle and gross vehicle weights
• Figure 12. Photo. Mini site-specific SMP weather station used to record climatic data
• Figure 13. Equation. Reflection cracking model
• Figure 14. Equation. IRI prediction model
• Figure 15. Equation. Flexible pavement design equation
• Figure 16. Equation. SN
• Figure 17. Flowchart. Partial set of construction event combinations and schedule of activities for example 1

LIST OF TABLES

• Table 1. Reflection cracking or IRI construction triggers-threshold limits
• Table 2. Reflective cracking model parameter d
• Table 3. Network-level construction trigger-threshold limits
• Table 4. Project-level construction trigger-threshold limits
• Table 5. RSI based on PSR values and construction treatment
• Table 6. Construction trigger-threshold limits matrix
• Table 7. RSI based on construction treatments

LIST OF ABBREVIATIONS

EXECUTIVE SUMMARY

The remaining service life (RSL) concept has been around for decades and is well entrenched in the pavement community. It is used at all levels of the pavement management decisionmaking process to plan for future field construction events. However, there is no single, clear, widely accepted definition of RSL. Moreover, there is a great deal of uncertainty associated with the definition, especially with the use of the term "life" to represent different points in a pavement’s construction history. In addition, "life" is interpreted differently by stakeholders.

To overcome the RSL shortcomings, this report introduces terminology that removes the word "life" from the lexicon. Instead, the new terminology, known as the remaining service interval (RSI), introduces the concept of time remaining until a defined construction event is required. Pavements are comprised of interrelated structural parts that can be maintained, preserved, restored, rehabilitated, or reconstructed to serve the intended transportation needs.

The RSI concept does not provide an alternative to assessing the health of the network or making decisions about where to spend the available funds. It simply provides a clear terminology and a logical process that will create consistent construction event-based terminology and understanding (i.e., types of construction events and the timing of those events within the concept of life-cycle cost (LCC), risk analyses, and other prioritization approaches based on streams of future construction events and benefits to facility users).