Estimating Life Expectancies of Highway Assets, Volume 1: Guidebook (2012)

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N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP REPORT 713 Estimating Life Expectancies of Highway Assets Volume 1: Guidebook Paul D. Thompson Kevin M. Ford Mohammad H. R. Arman Samuel Labi Kumares C. Sinha Arun M. Shirole School of civil EnginEEring PurduE univErSity West Lafayette, IN Subscriber Categories Administration and Management • Economics • Highways TRANSPORTAT ION RESEARCH BOARD WASHINGTON, D.C. 2012 www.TRB.org Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration

NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation develops increasingly complex problems of wide interest to highway authorities. These problems are best studied through a coordinated program of cooperative research. In recognition of these needs, the highway administrators of the American Association of State Highway and Transportation Officials initiated in 1962 an objective national highway research program employing modern scientific techniques. This program is supported on a continuing basis by funds from participating member states of the Association and it receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board of the National Academies was requested by the Association to administer the research program because of the Board’s recognized objectivity and understanding of modern research practices. The Board is uniquely suited for this purpose as it maintains an extensive committee structure from which authorities on any highway transportation subject may be drawn; it possesses avenues of communications and cooperation with federal, state and local governmental agencies, universities, and industry; its relationship to the National Research Council is an insurance of objectivity; it maintains a full-time research correlation staff of specialists in highway transportation matters to bring the findings of research directly to those who are in a position to use them. The program is developed on the basis of research needs identified by chief administrators of the highway and transportation departments and by committees of AASHTO. Each year, specific areas of research needs to be included in the program are proposed to the National Research Council and the Board by the American Association of State Highway and Transportation Officials. Research projects to fulfill these needs are defined by the Board, and qualified research agencies are selected from those that have submitted proposals. Administration and surveillance of research contracts are the responsibilities of the National Research Council and the Transportation Research Board. The needs for highway research are many, and the National Cooperative Highway Research Program can make significant contributions to the solution of highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement rather than to substitute for or duplicate other highway research programs. Published reports of the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM are available from: Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet at: http://www.national-academies.org/trb/bookstore Printed in the United States of America NCHRP REPORT 713, VOLuME 1 Project 08-71 ISSN 0077-5614 ISBN 978-0-309-21407-0 Library of Congress Control Number 2012937137 © 2012 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, or Transit Development Corporation endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The project that is the subject of this report was a part of the National Cooperative Highway Research Program, conducted by the Transportation Research Board with the approval of the Governing Board of the National Research Council. The members of the technical panel selected to monitor this project and to review this report were chosen for their special competencies and with regard for appropriate balance. The report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the Governing Board of the National Research Council. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board, the National Research Council, or the program sponsors. The Transportation Research Board of the National Academies, the National Research Council, and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the object of the report.

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. On the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Charles M. Vest is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, on its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. Charles M. Vest are chair and vice chair, respectively, of the National Research Council. The Transportation Research Board is one of six major divisions of the National Research Council. The mission of the Transporta- tion Research Board is to provide leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Board’s varied activities annually engage about 7,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individu- als interested in the development of transportation. www.TRB.org www.national-academies.org

C O O P E R A T I V E R E S E A R C H P R O G R A M S CRP STAFF FOR NCHRP REPORT 713, VOLuME 1 Christopher W. Jenks, Director, Cooperative Research Programs Crawford F. Jencks, Deputy Director, Cooperative Research Programs Andrew C. Lemer, Senior Program Officer Sheila A. Moore, Senior Program Associate Eileen P. Delaney, Director of Publications Hilary Freer, Senior Editor NCHRP PROJECT 08-71 PANEL Field of Transportation Planning—Area of Forecasting Mark B. Nelson, Minnesota DOT, St. Paul, MN (Chair) Lacy D. Love, Volkert, Inc., Raleigh, NC Don W. Clotfelter, Washington State DOT, Tumwater, WA Gerardo Flintsch, Virginia Polytechnic Institute and State University, Blacksburg, VA Michael Plunkett, PowerPlan Consultants, Atlanta, GA Raymond S. Tritt, California DOT, Sacramento, CA Nastaran Saadatmand, FHWA Liaison Nadarajah “Siva” Sivaneswaran, FHWA Liaison Frank N. Lisle, TRB Liaison Martine A. Micozzi, TRB Liaison

This two-volume report provides a methodology for estimating the life expectancies of major types of highway system assets, in a form useful to state departments of transportation (DOTs) and others, for use in lifecycle cost analyses that support management decision making. Volume 1 is a guidebook for applying the methodology in DOT asset management policies and programs. Volume 2 describes the technical issues and data needs associated with estimating asset life expectancies and the practices used in a number of fields—such as the energy and financial industries—to make such estimates. The deterioration of highway infrastructure begins as soon as it is put into service. Effective management of highway system assets requires a good understanding of the life expectancy of each asset. Asset life expectancy is the length of time until the asset must be retired, replaced, or removed from service. Determining when an asset reaches the end of its service life generally entails consideration of the cost and effectiveness of repair and maintenance actions that might be taken to further extend the asset’s life expectancy. Different types of assets, such as pavements, bridges, signs, and signals, will have very different life expec- tancies. Asset life expectancy also depends on the materials used; demands actually placed on the asset in use; environmental conditions; and maintenance, preservation, and reha- bilitation activities performed. Effective management of highway system assets requires that agency decision makers design and execute programs that maintain or extend the life of the various types of assets in the system at low cost. Designers use estimates of asset life expectancy in their lifecycle cost analyses to make design decisions, but those estimates depend on assumptions about maintenance practices, materials quality, service conditions, and characteristics of the asset’s use. If actual service conditions and maintenance activities subsequently differ from the designer’s assumptions, the asset’s life is likely to be different from initial estimates. Better information and tools for estimating asset life expectancies are needed to guide in- service asset management programs. Research is needed to determine the life expectancies of assets for at least four potential cases: (1) when maintenance and preservation activities are performed as assumed by the designer in the lifecycle cost analysis, (2) when little or no maintenance is performed over the life of the asset, (3) when more aggressive maintenance and preservation activities are performed to extend the asset’s life, and (4) when materials or designs that require no or very little maintenance are used. The objectives of NCHRP Project 8-71 were to (1) develop a methodology for determining the life expectancies of major types of highway system assets for use in lifecycle cost analyses that support management decision making; (2) demonstrate the methodology’s use for at least three asset classes, including pavement or bridges and two others, such as culverts, F O R E W O R D By Andrew C. Lemer Staff Officer Transportation Research Board

signs, or signals; and (3) develop a guidebook and resources for use by state DOTs and others for applying the methodology to develop highway maintenance and preservation programs and assess the effect of such programs on system performance. A research team led by Purdue University, West Lafayette, Indiana, conducted the research. The project entailed a review of current literature and practices within highway agencies and other industries, such as utilities and vehicle- and equipment-fleet manage- ment, to describe the methodologies currently used to determine life expectancy for major assets. The research team considered both new and in-service highway assets (such as pave- ments, bridges, culverts, signs, pavement markings, guardrail, and roadside facilities), and described the factors likely to influence predicted or assumed asset life expectancies. These factors include materials, design criteria, construction quality control, and maintenance policies and practices. Data needs and availability influence analytical ability to estimate and predict asset life expectancies. Geographic location and highway system management poli- cies also influence life expectancies. Considering these factors, the research team described methodologies for estimating the life expectancy of major types of highway system assets, for use in lifecycle cost analyses that support maintenance and preservation management decision making. The research produced this two-volume report. Volume 1 is a guidebook designed to be used by transportation agency staff wishing to estimate asset life expectancies. The guide will be useful to agency staff and their advisors in developing asset management and main- tenance systems, policies, and programs. Volume 2 documents the research project and pre- sents background information and research results that will be useful to other researchers and practitioners wishing to know more about the theories and methods for estimating asset life expectancies.

1 Chapter 1 Introduction: How to Use This Guide 2 1.1 Who Should Use This Guide 3 1.2 Setting Goals and Objectives 3 1.3 Listing Desired Applications 5 1.4 Delimiting the Scope of the Effort 6 1.5 Assessing Gaps and Readiness 8 1.6 How to Use This Guide 11 Chapter 2 Plan for Implementation: How to Plan Life Expectancy Models 12 2.1 Documenting Business Processes 12 2.2 Planning the Change Strategy 13 2.3 Listing Desired Reports and Tools 14 2.3.1 Data Storage 15 2.3.2 Foundation Analysis Tools 15 2.3.3 Applications and Reports 17 2.4 Defining the Work Plan and Resource Needs 18 2.5 Setting Quality Metrics and Milestones 20 Chapter 3 Establish the Framework: How to Design Life Expectancy Models 21 3.1 Defining Performance Measures 24 3.2 Conceptualizing the Analysis 24 3.2.1 Defining End-of-Life 27 3.2.2 Intervention Possibilities 27 3.2.3 Modeling Performance and Uncertainty 29 3.3 Determining Data Requirements 31 3.4 Mocking Up Tools and Reports 31 3.5 Gaining Buy-in and Building Demand 35 Chapter 4 Develop Foundation Tools: How to Compute Life Expectancy Models 37 4.1 Example Life Expectancy Models 37 4.1.1 Culverts 42 4.1.2 Traffic Signs 47 4.1.3 Traffic Signals 50 4.1.4 Roadway Lighting 53 4.1.5 Pavement Markings 56 4.1.6 Curbs, Gutters, and Sidewalks 57 4.1.7 Pavements 62 4.1.8 Bridges 67 4.1.9 Other Asset Types 68 4.1.10 Summary Estimates C O N T E N T S

68 4.2 Developing Life Expectancy Models 69 4.2.1 Ordinary Regression of Age at Replacement 77 4.2.2 Markov Model 81 4.2.3 Weibull Survival Probability Model 86 4.2.4 Cox Survival Probability Model 86 4.3 Validating and Refining Models 89 Chapter 5 Develop Applications: How to Apply Life Expectancy Models 89 5.1 Deterioration Models and Life Expectancy 89 5.1.1 Regression of Condition 92 5.1.2 Markov Models 97 5.1.3 Markov/Weibull Models 98 5.1.4 Ordered Probit 100 5.1.5 Machine Learning 101 5.1.6 Mechanistic Models 101 5.2 Building Blocks of Life Expectancy Applications 101 5.2.1 Equivalent Age 104 5.2.2 Life Extension Benefits of Actions 105 5.2.3 Remaining Life 106 5.2.4 Lifecycle Cost Models 111 5.3 Example Applications 112 5.3.1 Routine Preventive Maintenance 113 5.3.2 Optimal Replacement Interval 114 5.3.3 Comparing and Optimizing Design Alternatives 114 5.3.4 Comparing and Optimizing Life Extension Alternatives 116 5.3.5 Pricing Design and Preservation Alternatives 116 5.3.6 Synchronizing Replacements 118 5.3.7 Effect of Funding Constraints 119 5.3.8 Value of Life Expectancy Information 120 5.3.9 Highway Asset Valuation 121 5.4 Role of a User Group 123 5.5 Development of Applications 124 Chapter 6 Accounting for Uncertainty: How to Improve Life Expectancy Models 125 6.1 Sensitivity Analysis of Life Expectancy Models 128 6.2 Risk Analysis of Life Expectancy Models 129 6.2.1 Example Risk Assessment of Uncertain Life Expectancy Factors 131 6.2.2 Example Risk Assessment of Uncertain Estimates of Asset Life 134 Chapter 7 Ensure Implementation: How to Improve Life Expectancy Models 134 7.1 Measuring and Promoting Success 135 7.2 Incorporation into Management Systems 137 Chapter 8 Conclusions 138 References Note: Many of the photographs, figures, and tables in this report have been converted from color to grayscale for printing. The electronic version of the report (posted on the Web at www.trb.org) retains the color versions.