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  • Draft

    Code of Practicefor the

    Rehabilitation of Road PavementsSeptember 1998

    (Reprinted July 2001)

    Prepared by the Division of Roads and Transport Technology, CSIR

  • i

    PREFACE AND ACKNOWLEDGEMENT

    This document is based closely on the South African guide to pavement rehabilitation, Draft TRH12:Pavement rehabilitation investigation and design, 1997. A number of detailed changes of varyingsignificance have been introduced in order to make the guide more appropriate to the SADC region, butthe basic format and content follows that of TRH12.

    The cooperation of the South African Committee of State Road Authorities in granting permission tomake use of TRH12 as the basis for this document is gratefully acknowledged.

  • ii

    TABLE OF CONTENTS

    LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

    LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

    1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11.2 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11.3 Managing Pavement Rehabilitation Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-21.4 Recommended Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-41.5 Management Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

    2. PAVEMENT CONDITION ASSESSMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12.2 Initial Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12.3 Detailed Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-25

    3. REHABILITATION DESIGN APPROACH AND OPTIONS . . . . . . . . . . . . . . . . . . . . . . . 3-13.1 Objectives and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13.2 Rehabilitation Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13.3 Method Applicability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-23.4 Pavement Rehabilitation Design Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

    4. PRACTICAL AND FUNCTIONAL ASPECTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14.2 Applicability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14.3 Constructability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-24.4 Performance Adequacy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-34.5 Maintainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

    5. ECONOMIC ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15.2 Agency costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-35.3 Road User Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-45.4 Principles of the Economic Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-65.5 Incorporating Uncertainty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8

    6. GLOSSARY OF TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

    7. REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

    APPENDIX A: CONDITION ASSESSMENT: PERFORMANCE CRITERIA FOR THE EVALUATION OFPAVEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

    A.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1A.2 Visually Recorded Distress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3A.3 Mechanical Pavement Surveillance Measurements . . . . . . . . . . . . . . . . . . . . . . . . A-5A.4 Pavement Evaluation Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-8

  • iii

    APPENDIX B: PAVEMENT REHABILITATION DESIGNS USED IN SOUTHERN AFRICA:PRINCIPLES AND MAIN CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

    B.1 Asphalt Institute Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1B.2 The DCP Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-4B.3 The TRL Surface Deflection Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-7B.3 Shell Overlay Design Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-10B.4 The South African Mechanistic Design Method . . . . . . . . . . . . . . . . . . . . . . . . . . . B-14

    APPENDIX C: CONCEPTS IN DECISION THEORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

    APPENDIX D: EXAMPLE: ECONOMIC ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1D.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1D.2 Sections Requiring Structural Strengthening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1D.3 Sections Requiring Resealing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-4

  • iv

    LIST OF TABLES

    Table 2.1: Modes and types of distress and their typical codes . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4Table 2.2: Classification of degrees of distress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5Table 2.3: Nominal road categories adopted for pavement rehabilitation design . . . . . . . . . . . . . . 2-8Table 2.4: Percentile levels recommended for data processing . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10Table 2.5: Recommended relative damage exponents, n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11Table 2.6: Estimation of average ESAs per heavy vehicle class . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12Table 2.7: Converting thickness of existing pavement components to Effective Thickness9 . . . . 2-23Table 2.8: Summary of measurements most commonly used during a detailed assessment . . . 2-28Table 2.9: Nominal pavement state from deflection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-29Table 2.10: Typical surfacing life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-39Table 3.1: Critical parameters and properties associated with various material types . . . . . . . . . . 3-4Table A.1: Typical unit lengths for the processing of project level data . . . . . . . . . . . . . . . . . . . . . . A-3Table A.2: Performance criteria for visually recorded distress . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-4Table A.3: Percentile levels recommended for data processing . . . . . . . . . . . . . . . . . . . . . . . . . . . A-5Table A.4: Performance criteria recommended for the assessment . . . . . . . . . . . . . . . . . . . . . . . . A-5Table A.5: Criteria recommended for the assessment of structural condition . . . . . . . . . . . . . . . . . A-6Table A.6: Summary of the most commonly used deflection bowl parameters . . . . . . . . . . . . . . . A-8Table C.1: Resultant outcomes and actions for two time periods for any one initial action . . . . . . C-2

  • v

    LIST OF FIGURES

    Figure 1.1: Main elements of the various inputs influencing rehabilitation design . . . . . . . . . . . . . . 1-7Figure 2.1: Flow diagram of the pavement initial assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2Figure 2.2: Relationship between standard deflection and life: granular road bases . . . . . . . . . . 2-16Figure 2.3: Relationship between standard deflection and life: granular road bases with

    natural cementing action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17Figure 2.4: Relationship between standard deflection and life: bituminous road bases . . . . . . . . 2-17Figure 2.5: Relationship between standard deflection and life: cement-bound road bases . . . . . 2-18Figure 2.6: Design example for pavements with granular road bases whose aggregates

    exhibit a natural cementing action (from Figure 2.3) . . . . . . . . . . . . . . . . . . . . . . . 2-19Figure 2.7: Relationship between pavement bearing capacity and DSN800 . . .