current measurement efforts are undertaken because they are mandated by federal or state governments or as an ad hoc response to a perceived problem or the demands of an impending short-term project. The interactions among infrastructure elements, for example, transportation and wastewater, are seldom explicitly considered and are even less frequently reflected in management policy. Despite the importance of measurement, current practices of measuring comprehensive system performance are generally inadequate to provide a comprehensive basis for effective decision making.
The recent changes in federal government policy are intended to improve performance assessment. This study seeks to contribute to this effort in three ways: (1) by developing a process and framework that take a multimodal and systemwide perspective, (2) by limiting assessment to social objectives, and (3) by dealing explicitly with the multiple decision makers and levels of governments involved in infrastructure management.
Together with this introduction, Chapter 2 presents the committee's basic definitions of infrastructure performance and how its measurement may be used in managing a metropolitan area's infrastructure. Chapters 3 and 4 present the committee's recommended process and framework for measurement and for using performance measures in decision making. Chapter 4 in particular recommends the dimensions and broad measures of infrastructure performance and suggests examples of specific indicators for the four broad categories of infrastructure included within the study's primary focus.
Chapter 5 deals with a number of considerations related to implementing performance-based infrastructure management in a metropolitan area. Chapter 6 summarizes the committee's principal findings and conclusions (indicated in boldface type throughout the report) and its recommendations for measuring and improving infrastructure performance. These chapters outline the actions to be taken to put the committee's performance measurement framework into practice.
The precise meaning and scope of the term ''infrastructure'' continue to be the subject of discussion (e.g., see NRC 1987, 1993). The committee responsible for this report agreed with earlier NRC studies that "infrastructure" necessarily encompasses both facilities and their operations. Refer to Appendix E. As explained, this report's scope is for the most part limited to the range of modes covered in the work of the National Council on Public Works Improvement (NCPWI, 1988).