because they measure only certain aspects of demand or supply" (NCPWI, 1988). The NCPWI then commissioned new studies to undertake "an assessment of the performance of the nation's infrastructure," which measured performance in terms of "four measures: physical assets, product delivery, quality of service, and cost-effectiveness." Table 2-1 presents ''illustrative measures" the NCPWI cited for physical assets, product delivery, and quality of service. The NCPWI report only hints, however, at a clear definition for the term "performance,'' saying simply that "demand for and supply of public works services jointly determine performance levels and the quality of services provided" (NCPWI, 1988).

A necessary early step in this study therefore was adopting an explicit definition of performance. The committee agreed that no single indicator or index is likely to be a sufficient practical measure of infrastructure performance. Table 2-1 thus became the point of departure for the committee's efforts, and in key aspects the committee diverged substantially from the NCPWI's earlier work.

THE BASIC CONCEPT OF PERFORMANCE

If "performance" is, as a dictionary defines it, the execution of a task or fulfillment of a promise or claim, then infrastructure performance is the accomplishment of tasks set for the system or its parts by the society that builds, operates, uses, or is neighbor to that infrastructure. In short, the bases for measuring infrastructure performance are defined by the broad community. As has already been noted, this community includes national-and state-level as well as local perspectives. As a consequence, there generally may be many measures of performance, and they may vary from place to place.

The tasks the community wants its infrastructure to accomplish initially have to do with moving goods and people or providing clean water, but society sets broader tasks as well. Infrastructure provides jobs to the people who construct, operate, and maintain its facilities and services. By providing more or better services in some regions or to some social groups, infrastructure fosters differential patterns of income, economic opportunity, and growth. As a market and test bed for new technologies, infrastructure enhances or retards technological innovation and the resulting growth of economic productivity. The public objection that its facilities sometimes engender is evidence that infrastructure is failing to meet social, cultural, or aesthetic purposes. The effectiveness of infrastructure as a public investment serving these broader ends also is an essential aspect of infrastructure performance.1

It would be tempting to suppose that a simple indicator of infrastructure performance could be devised, a single index of how well the system



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