Strategic Issues Facing Transportation, Volume 7: Preservation, Maintenance, and Renewal of Highway Infrastructure (2020)

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7 Report Overview and Organization This report summarizes the work performed in National Cooperative Highway Research Program (NCHRP) Project 20­83(03)A, “Long­Range Strategic Issues Affecting Preservation, Maintenance, and Renewal of Highway Infrastructure.” The report is organized by eight chap­ ters. Chapter 1 (this chapter) provides an overview of the project, its objectives, and the research methodology. The chapter also describes the definitions of highway infrastructure preservation, maintenance, and renewal (PMR). Chapter 2 describes the future factors and trends (drivers) that could significantly influence highway infrastructure PMR. The chapter also discusses the scenarios or possible futures that will emerge because of these drivers and their implications on PMR and provides a summary of the literature review on future drivers. Chapter 3 describes an assessment of the emerging PMR practices required in response to the drivers and scenarios, discusses their implications on PMR, lists and prioritizes more than 60 PMR­focused emerging practices, and identifies the 16 emerging practices that are most responsive to drivers and of most interest to agencies. Chapter 4 discusses the benefits of implementing each of the identified emerging PMR practices and presents a summary­level categorization of the benefits. Chapter 5 examines the potential risks and challenges (barriers) associated with each identified emerging PMR practice along with an analysis of the common barriers and means to overcome them. Chapter 6 discusses the capability maturity methodology that can be used by transportation agencies in advancing desirable emerging and innovative practices toward implementation. Chapter 7 summarizes the resources developed and how to use them. Chapter 8 provides a sum­ mary of research and its findings. In addition, two guides are provided. One guide, the Practitioner’s Guide to Emerging Highway Preservation, Maintenance, and Renewal Practices (Part B of this report) is intended to assist trans­ portation professionals on the application of emerging and innovative practices and addresses long­range (30 to 50 years) highway infrastructure preservation, maintenance, and renewal. The other guide, the Leadership’s Guide to Emerging Highway Preservation, Maintenance, and Renewal Practices (Part C of this report) is intended to stimulate interest among leaders of transportation agencies in fostering emerging and innovative practices relevant to PMR. Research Objectives and Background The objective of this project was to develop guidance for transportation stakeholders on the application of emerging and innovative materials, tools, approaches, and technologies to deal with long­range (30 to 50 years) highway infrastructure PMR needs. For the purpose of this report, PMR practices refer to any or all aspects of PMR operations (e.g., materials, technologies, approaches, and tools). C H A P T E R 1 Introduction

8 Strategic Issues Facing Transportation Project Context This project is part of a series of seven NCHRP studies initiated to examine long­range (30 to 50 years into the future) strategic issues that will likely affect transportation organizations (TOs). The other six topics in the series are: • NCHRP 20­83(01): Economic Changes Driving Future Freight Transportation. • NCHRP 20­83(02): Expediting Future Technologies for Enhancing Transportation System Performance. • NCHRP 20­83(04): Preparing State Transportation Agencies for an Uncertain Energy Future. • NCHRP 20­83(05): Climate Change and the Highway System: Impacts and Adaptation Approaches. • NCHRP 20­83(06): Effects of Socio­Demographics on Travel Demand. • NCHRP 20­83(07): Sustainability as an Organizing Principle for Transportation Agencies. These projects were completed and the findings published as NCHRP Report 750: Strategic Issues Facing Transportation in Volumes 1 through 6 (Caplice and Phadnis, 2013; Meyer et al., 2014; Popper et al., 2013; Booz Allen Hamilton, 2014; Sorenson et al., 2014; Zmud et al., 2014). An initial phase of this research was completed under NCHRP Project 20­83(03) and produced two interim reports: Phase I Interim Report (TTI, 2012) and Task 6 (Phase II Interim) Report (TTI, 2014). This project identified PMR­specific drivers, scenarios, and emerging practices. Maintaining a Focus on Emerging and Innovative Practices Future PMR practices are more likely to evolve than to arise in sudden transformations. How­ ever, decades of evolutionary steps will very likely result in profound transformations, particu­ larly when catalyzed/energized by influences from broader domains that entail a wide range of potential applications, such as advancements in information technologies and materials science. In addressing such change over a long period of time, this research will balance several needs that often compete for attention: • The need to keep streets and highways operational and in a state of good repair with a mini­ mum of disruption, without compromising safety, and with customer interest in mind. • The need to rebuild or improve existing facilities when physical or functional deficiencies can no longer be tolerated nor corrected with limited interventions. • The need to respond and adapt to a range of future possibilities that will affect the physical integrity and operational services provided by the highway infrastructure. • The need to be proactive in addressing highway system PMR. • The need to anticipate, shape, and adapt to long­term future trends and advancements, while responding to today’s needs. PMR Definitions To pursue this research, it was necessary to define the terms preservation, maintenance and renewal as they might apply into the future and also understand how these definitions evolved and have been used over time. Some of the national discourse around these topics is presented in Appendix A (available as part of NCHRP Web-Only Document 272 from trb.org by searching for “NCHRP Report 750, Volume 7”).

Introduction 9 While the terms maintenance, preservation, and renewal have been defined in many different ways, there has been some convergence of opinion in terms of what they mean. FHWA’s most recent guidance (Waidelich, 2016) does not address renewal but it provides an important dis­ tinction between maintenance and preservation and also between preventive maintenance and routine maintenance. Moreover, this guidance ties the concepts of preservation to performance management (through linkage to the state of good repair)—a concept that will likely increase in importance over time. Therefore, these FHWA definitions were used in this research with some adaptation to make them asset neutral, time invariant, and forward looking in terms of potential for inclusivity of other highway infrastructure asset and service classes. • Preservation: Includes work activities that are planned and performed to improve or sustain the asset condition in a state of good repair. Asset preservation primarily includes preventive maintenance, minor rehabilitation and retrofitting of infrastruc­ ture elements [pavements, bridges, intelligent transportation system (ITS) or ITS components], network or area wide enhancements and upgrades, and some aspects of routine maintenance. – Preventive maintenance includes a series of cost­effective treat­ ments applied to preserve or extend the service life, retard future deterioration, upgrade to current or improved safety standards, and maintain or improve the functional conditions of existing assets. Both condition­based and regularly scheduled cyclical activities that contribute to extending the useful life of assets are considered preventive maintenance activities. – Minor rehabilitation involves non­structural enhancements to either reduce aging, restore serviceability, or eliminate surface­ initiated, environmentally induced deterioration. Network or area wide enhancements, such as for pavement striping, lighting components, signs, and guardrails, are also considered. – All planned and recurring activities of routine maintenance per­ formed to reduce the deterioration of existing assets are consid­ ered preservation. • Maintenance: Describes work activities performed to maintain the general condition of exist­ ing assets or in response to specific conditions or events to restore an asset’s functional state. Maintenance includes some aspects of routine maintenance, corrective maintenance, and emergency maintenance. – Routine maintenance performed to restore functional condition of existing assets, such as crack filling of non­working cracks, dust control, spot painting, snow removal, debris removal, mowing and tree removal, fender systems repair, weed and vegetation control, and drainage cleaning. – Corrective and emergency maintenance include “reactive” types of work activities per­ formed in response to potential or existing deficiencies that adversely impact the smooth and safe operations and future integrity of the existing asset. Examples include pothole repairs, bridge deck joint repairs, patching and grouting, full or partial depth repair, and bridge bearings replacement. • Renewal: Includes work activities performed to fully or partially restore the structural integ­ rity, correct safety defects, and improve functional capability of the asset. – Major rehabilitation involves major work required to enhance or restore the structural integrity of an asset as well as work necessary to correct major functional deficiencies and safety defects. It is recognized that preferences for specific definitions will vary among agencies and professionals. Also, in defin ing Preservation, Maintenance, and Renewal—particularly while draw­ ing upon some of the more commonly accepted definitions from prior work—it is not possible to avoid some degree of overlap where a particular activity may well be applicable to more than one of the three PMR categories. With these considerations in mind, readers should focus more on the underlying meanings of the principles and practices being discussed than on the broad and imper­ fectly aligned definitions of PMR.

10 Strategic Issues Facing Transportation – Reconstruction involves a complete removal and replacement of a structurally deficient or functionally obsolete asset with an equivalent or enhanced service capacity. Research Approach This research focused on providing technical guidance for transportation leaders and prac­ titioners to address the long­range PMR needs of highway infrastructure while considering emerging PMR practices. NCHRP Project 20­83(03) has addressed some of the more philo­ sophical and futuristic scenario­based aspects of the topic (TTI, 2014). This work, together with other documented research, was used to identify drivers, scenarios, and potential emerging PMR practices for assessment in this project (while staying away from predicting future “states of the world” as is done in scenario visioning exercises). This approach is consistent with a key conclu­ sion of this earlier study (TTI, 2014), which notes that the higher­order organization of scenarios into “(future) worlds” does not alter the nature of the innovations that need to be identified or the guidance that needs to be developed in order to successfully prepare for the plausible futures. Figure 1 presents an overview of the research approach, including the major work phases and activities within each phase.

Introduction 11 Figure 1. Overview of the research approach. ACTIVITY NAME ACTIVITY HIGHLIGHTS Scenarios and Impacts Vision Development Guidance and Communication Deliverables • Focused review and identification of driver categories, corresponding scenarios and scenario elements • Identify driver implications on PMR through scenario lenses • Identify & characterize emerging PMR strategies to address driver implications • Select and characterize top 24 PMR strategies or strategy areas • Evaluate emerging PMR strategies in terms of their ability to meet needs, their beneficial impacts, the extent of TO business and technology change management needed • Document barriers and opportunities for enhancing practice • Synthesize emerging PMR strategies across scenarios and consolidate into 4 groups— materials, approaches, tools & technologies • Articulate implementation-focused vision for sustainable infrastructure • Develop and deliver project deliverables • Perform analysis of drivers for top innovations to establish interconnectedness and identify key drivers of change • Identify primary target audience and communications strategies • Develop implementation guidance for target audience identifying triggers to initiate change management, which technologies to implement, and when and how • Develop capability maturity model to track implementation progress • Identify gaps in study and areas of further research