Appendix F
GLOSSARY

Several professional disciplines share interest in issues of infrastructure performance. Each discipline adopts terminology that may have precise or generally accepted meaning for members of that discipline, but may differ from the terminology of other disciplines or common usage. In conducting their study, the committee frequently used the following terms and found it helpful to agree on their definitions. (Terms shown in italics in definitions are themselves defined.)


Assessment.

Judgment of the adequacy, acceptability, or value of behavior or characteristics of a system; generally based on observation or measurement.


Benefit.

Impact or result of an action or event related to building, operating, maintaining, or using infrastructure, not necessarily related to the tasks that infrastructure is intended to accomplish; may be positive or negative, in the latter case, may be termed disbenefit.

Benchmark.

A basis for comparison derived from past behavior or characteristics of a system or comparable systems, against which current behavior or characteristics of the system may be judged; not a standard, although standards may be adopted from benchmarks.


Community.

A group or several groups of people and institutions drawn together by common interest in development and management of infrastructure; may include local, regional, state, and national perspectives.

Cost.

See system cost.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 120
Measuring and Improving Infrastructure Performance Appendix F GLOSSARY Several professional disciplines share interest in issues of infrastructure performance. Each discipline adopts terminology that may have precise or generally accepted meaning for members of that discipline, but may differ from the terminology of other disciplines or common usage. In conducting their study, the committee frequently used the following terms and found it helpful to agree on their definitions. (Terms shown in italics in definitions are themselves defined.) Assessment. Judgment of the adequacy, acceptability, or value of behavior or characteristics of a system; generally based on observation or measurement. Benefit. Impact or result of an action or event related to building, operating, maintaining, or using infrastructure, not necessarily related to the tasks that infrastructure is intended to accomplish; may be positive or negative, in the latter case, may be termed disbenefit. Benchmark. A basis for comparison derived from past behavior or characteristics of a system or comparable systems, against which current behavior or characteristics of the system may be judged; not a standard, although standards may be adopted from benchmarks. Community. A group or several groups of people and institutions drawn together by common interest in development and management of infrastructure; may include local, regional, state, and national perspectives. Cost. See system cost.

OCR for page 120
Measuring and Improving Infrastructure Performance Design lifetime. The period of time, assumed as a basis for making feasibility studies and design decisions, during which a facility of element is anticipated to provide service; for infrastructures, typically 15 to 50 years. Not necessarily the same as service life or economic life. Dimension (of effectiveness). A single aspect of effectiveness that can be discussed and assessed with minimal reference to other aspects (e.g., traffic congestion on a highway versus the stormwater runoff from that highway)—in principle, linked directly to goal or task set for infrastructure. Disbenefit. A negative benefit; an adverse impact or consequence. Economic life. The period of time over which infrastructure is expected to repay its full cost. Often determined by financial factors as well as technical. Effectiveness. A multidimensional component of performance; the degree to which infrastructure accomplishes the tasks set for it by its owners, users, neighbors, and society-at-large. Evaluation. Assessment in which tradeoffs may be made among disparate and generally incommensurable measures, especially for determining preference among several complex alternative courses of action. Indicator. A measure, but often not very specific in its information about effectiveness; for example, the color red is frequently used as an indicator of high temperature, which is in turn a measure of heat energy or risk of burning. Infrastructure. Not specifically defined in this study; generally used in this report to refer to facilities and their operations and the operating and management institutions that provide water, remove waste, facilitate movement of people and goods, and otherwise serve and support other economic and social activity or protect and enhance environmental quality. Refer to cited references for further discussion (e.g., NRC, 1987; NCPWI, 1988; NRC, 1993). Level of service. A measure of effectiveness; frequently used for transportation infrastructure and most well developed for highway and street traffic capacity analysis (e.g., see TRB, 1985). Measure, measure of effectiveness. A sign, symbol, or statistic (typically numerical) that people understand to convey information about how well infrastructure is accomplishing its tasks, typically for a single dimension of effectiveness; may be based on some generally used scale (e.g., water or traffic volumes) or defined relative to a benchmark (e.g., observed throughput as a fraction of theoretical maximum throughput) or standard (e.g., observed pollution concentration as a fraction of the level allowable under law). A specific indicator. Measurement. Structured observation and documentation of one or more aspects of the behavior or characteristics of a system. Implies no assessment or evaluation.

OCR for page 120
Measuring and Improving Infrastructure Performance Performance. The degree to which infrastructure provides the services that the community expects of it; a function of effectiveness, reliability, and cost. Reliability. A component of performance; the likelihood that infrastructure effectiveness will be maintained over an extended period of time; the probability that service will be available at least at specified levels throughout the design lifetime of the infrastructure system. Service life. The time over which infrastructure actually provides service to users; a result of operating and maintenance practices. Often exceeds economic life and design lifetime. Stakeholder. An individual or group within the community, having a particular interest, perspective, goals, or objectives that bear on how infrastructure performance is assessed. Standard. A basis for comparison and assessment of behavior or characteristics of a system, established by law, regulation, common practice, or consensus; may be derived from past behavior or characteristics of comparable systems. Compare benchmark. System. An assemblage or combination of elements forming a complex whole, e.g., the highways in a particular region; the assemblage of all the individual functional modes (e.g., water supply, transportation) of infrastructure that together serve and support economic and social activity or protect and enhance environment of a city or region. System cost. A component of performance; the resources required build, operate, and maintain infrastructure; typically measured in monetary terms. In appropriate context, also termed simply cost. Not the same as user cost. User cost. A dimension of effectiveness. The monetary or other direct expenditures that users must make to gain access or use infrastructure services; not the same as cost.