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FOREWORD Highway administrators, engineers, and researchers often face problems for which information already exists, either in documented form or as undocumented experience and practice. This infor- mation may be fragmented, scattered, and unevaluated. As a consequence, full knowledge of what has been learned about a problem may not be brought to bear on its solution. Costly research find- ings may go unused, valuable experience may be overlooked, and due consideration may not be given to recommended practices for solving or alleviating the problem. There is information on nearly every subject of concern to the highway administrators and engineers. Much of it derives from research or from the work of practitioners faced with problems in their day-to-day work. To provide a systematic means for assembling and evalu- ating such useful information and to make it available to the entire highway community, the American Association of State Highway and Transportation Officialsâthrough the mechanism of the National Cooperative Highway Research Programâauthorized the Transportation Research Board to undertake a continuing study. This study, NCHRP Project 20-05, âSynthesis of Informa- tion Related to Highway Problems,â searches out and synthesizes useful knowledge from all available sources and prepares concise, documented reports on specific topics. Reports from this endeavor constitute an NCHRP report series, Synthesis of Highway Practice. This synthesis series reports on current knowledge and practice, in a compact format, without the detailed directions usually found in handbooks or design manuals. Each report in the series provides a compendium of the best knowledge available on those measures found to be the most successful in resolving specific problems. PREFACE By Jo Allen Gause Staff Officer Transportation Research Board Current transportation asset management practices for low-volume roads typically use asset con- dition, traffic, and safety metrics to prioritize investment decisions for preservation, maintenance, repair, and replacement projects. However, these metrics do not fully measure the significant value for the wider economy and society that low-volume roads can provide. This synthesis documents current practices used by transportation agencies to make investment decisions about low-volume roads. The synthesis also addresses the challenges that decision makers may face to communicate the value of such investments to stakeholders in an era of limited funds and constantly changing demands on the transportation system. Information used in this study was gathered through a literature review, a survey of state depart- ments of transportation and Canadian provincial transportation agencies, and follow-up interviews with selected agencies. Six case examples provide additional information on the state of the practice for prioritization of low-volume roads. Naomi Stein, Glen Weisbrod, and Mark Sieber, Economic Development Research Group, col- lected and synthesized the information and wrote the report. The members of the topic panel are acknowledged on page iv. This synthesis is an immediately useful document that records the practices that were acceptable with the limitations of the knowledge available at the time of its preparation. As progress in research and practice continues, new knowledge will be added to that now at hand.
Note: Photographs, figures, and tables in this report may 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. 1 Summary 4 Chapter 1 Introduction 4 1.1 Background and Motivation 5 1.2 Study Approach and Synthesis Organization 6 Chapter 2 Review of the Literature 6 2.1 Introduction and Approach to the Literature 7 2.2 Defining and Understanding the Value of Low-Volume Roads 10 2.3 Prioritization Practice 19 2.4 Review of the LiteratureâKey Observations 21 Chapter 3 Survey of Agency Practice 21 3.1 Overview 21 3.2 Survey Instrument, Distribution, and Response 23 3.3 Survey Results: Experience with Prioritization of Low-Volume Roads 33 3.4 Survey of PracticeâKey Observations 35 Chapter 4 Case Examples 35 4.1 Overview 36 4.2 Individual Case Examples 48 4.3 Case ExamplesâKey Observations 50 Chapter 5 Conclusions 50 5.1 Motivation for Granting Low-Volume Roads Special Consideration 51 5.2 Approaches to Defining and Differentiating Low-Volume Roads 51 5.3 Methods for Prioritizing Low-Volume Road Investments 52 5.4 Evolving Issues in Low-Volume Road Planning and Management 52 5.5 Successes and Challenges in Current Practice 53 5.6 Knowledge Gaps and Suggestions for Future Research 55 References 59 Appendix A Survey Questionnaire 68 Appendix B Survey Respondents C O N T E N T S
1 Low-volume roads (LVRs) are at a disadvantage relative to other roads within traditional investment prioritization processes that focus on volume-based metrics of benefit and impact. However, LVRs can also create significant value for the wider economy and society, by providing basic access to remote communities, ensuring connectivity (particularly last- mile connectivity) for industry to a global economy, and supporting economic development opportunities. A growing recognition of the need to go beyond standard transportation asset management approaches to capture the importance of LVR investments in agency prioritization practice motivated this research. The report documents current practices used by transportation agencies to make invest- ment decisions about LVRs. The intention of the report is to help transportation officials in charge of resource allocation decisions at state departments of transportation (DOTs), as well as at regional and local agencies, respond to the challenge of accounting for broader economic, social, and environmental implications of LVR projects. The report also addresses the challenge that decision makers may face to communicate the value of such investments to stakeholders in an era of limited funds and constantly changing demands on the transpor- tation system. The primary focus of the synthesis is on investment prioritization methods. However, the research also touches on a range of decision-making issues including funding program definition, programmatic resource allocation, and other planning and management activities that directly affect investments made in LVRs. The principal intended audience of the research is practitioners within state DOTs. The objective of ensuring adequate investment in LVRs is particularly relevant to state DOTs because of the range of roadways they own, manage, and prioritize relative to one another on an ongoing basis. Municipalities and counties tend to have lower volume roads on their systems, in general, and therefore may not face the same challenges as states with priori- tization imbalances created by volume-based criteria. Nevertheless, this research can also offer value to engineers and planners within local governments and counties where there is interest in accounting for economic, social, and environmental impacts of LVR investments. The report discusses and presents the following: (a) review of North American and inter- national planning and prioritization literature for LVRs, including consideration of their definition, importance, and available evaluation methods; (b) results from a survey of state DOTs and Canadian provincial transportation agencies regarding their current approaches to LVR investment prioritization (40 out of 50 state DOTs completed the survey for a response rate of 80% and three provinces also responded); and (c) six detailed case examples of the current state of the practice for prioritization of LVRs with a focus on how critical strategic issues, that is, the broader social, economic, and environmental importance of LVRs, are considered within an agencyâs process. S U M M A R Y Investment Prioritization Methods for Low-Volume Roads
2 Investment Prioritization Methods for Low-Volume Roads The literature review, survey responses, and case examples all point to common agree- ment that LVRs can be important in ways that go beyond the level of traffic they carry, and that their significance merits special consideration within the planning and resource alloca- tion process. Exactly how that special consideration is implemented varies across agencies, in part because of differing definitional approaches to LVRs, as well as to programs of work within the resource allocation process. A significant number of state DOTs do actually define LVRs as a distinct class, based on volume thresholds and/or alternate approaches that relate to an agencyâs overall road classification scheme. Even those agencies that do not adopt formal LVR definitions nevertheless describe the practice of dividing their networks into different classes that often correlate with volume to guide agency decision making. States additionally vary in the scope of the low mileage network for which they are respon- sible, with some states managing much larger overall systems than other states. Nearly all LVR investments in the United States are related to safety or state of good repair rather than to system expansion. Nevertheless, agencies clearly see value in maintaining existing LVRs because of their role in providing access to rural or isolated areas and support- ing economic activity (e.g., farming, logging, mining, or other industry), as well as for their network coverage role within the broader transportation system. When making decisions about how to prioritize LVR investments (whether against each other or against other invest- ments on higher volume facilities), decision makers typically begin with core quantitative data including asset condition and transportation-related conditions or impacts (e.g., travel time or accident rates). At state transportation departments in the United States, these data are often organized and analyzed within pavement and bridge management systems. Recog- nizing that more traditional engineering analysis cannot capture all key decision variables, most transportation agencies then supplement with a mix of quantitative ratings, qualita- tive scoring (e.g., 0 to 10), and descriptive approaches to capture the economic, social, and environmental conditions or impacts of LVR investment decisions. The literature review also finds that there can be insights derived from both domestic and international experiences, including the body of research and practice from countries all along the development spectrum. While there are notable differences among countriesâ including the level of roadway infrastructure already in place and the available systems, data, expertise, and institutional capacity for managing that infrastructureâthere are never- theless key commonalities, particularly with respect to the economic development and basic access objectives of LVRs. The literature review provides examples of how to incorporate these common objectives into decision making in a way that extends beyond traditional engineering and asset management criteria. The literature review additionally includes documentation of different prioritization methods used globally including consumer and producer surplus based methods, processes for screening alternatives, benefitâcost/costâ benefit analysis, cost-effectiveness analysis, and multicriteria analysis. Focusing on state DOT practices, the individual case examples reveal the close relation- ship between statesâ desire to recognize the broader strategic importance of LVRs in serving communities and their reliance on local knowledge. In particular, because of their familiarity and close relationships to the communities they serve, district or field engineers help ensure that the prioritization process recognizes the broader (and often harder-to-quantify) role of LVRs. This recognition is achieved through processes with varying degrees of formality, ranging from open qualitative input to more structured use of qualitative scoring criteria. Quantitative measures of strategic importance are less common, although certain indicators such as measure of economic distress, poverty, or accessibility do appear in the literature as a way of raising one roadway or candidate project above another project. Funding limitations strongly influence the LVR prioritization conversation. Agency survey responses report a mix of perceptions of trends in LVR importance. On the one hand, some
Summary 3 agencies report decreased attention paid as funding constraints push agencies to direct their resources elsewhere. On the other hand, the same funding pressures are causing others to take a closer look at LVRs and their role within the broader transportation system. Going forward, LVRs may emerge as âfrontlinesâ in efforts to ârightsizeâ transportation system investments. When states grapple with the challenges of matching system size and invest- ment levels to societal needs, the ability to distinguish between different facilities with varying degrees of importance is likely to become even more critical. Also of note are the inter dependencies reported by transportation planners between federal policies and a state DOTâs decisions about LVRs; whereas performance management and target setting are focused in accordance with federal policy on the National Highway System, LVRs are typically not on this system, and therefore may receive a different level of attention. Most state DOTs report satisfaction with their current approaches to prioritizing LVR investments. In particular, the synthesis documents success experienced by states when implementing prioritization approaches that are flexible and able to incorporate local judg- ment and knowledge. Nevertheless, there were remaining knowledge gaps identified in the course of the synthesis that further research could address. The following are suggested topics that would benefit states and localities charged with managing and prioritizing LVRs: â¢ Structured best practices approaches to incorporate broader strategic objectives of LVR investments into decision making; â¢ Methods for jurisdictional transfer evaluation to support the goal of rightsizing highway networks; â¢ Guidance on interjurisdictional partnering and coordination in funding and prioritization of local LVR improvements; â¢ Approaches to optimizing tiered level of service targets as a function of agency and societal costs; and â¢ Understanding threshold effects from long-term reductions in LVR performance. The conclusions chapter discusses these research topics in more detail. Finally, it is worth noting that broader efforts to incorporate strategic objectives into resource allocation deci- sion processes in general may ultimately result in useful advancement in LVR prioritization practice.