Click for next page ( 2

The National Academies of Sciences, Engineering, and Medicine
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 1
Executive Summary RECOMMENDATION The Pane} on the Assessment of Wind Engineering Issues in the United States recommends the establishment of a national program to reduce wind vulnerabilitya National Wind Science and Engineering Program. Such a program, enacted by Congress and backed by a sustained bud~etarv commitment of $20 million per year for the first five years tas outlined later in Table 1-5), would catalyze the formulation of clearly articulated national goals regarding wind engineering and forecasting and establish resnon.sihili~v among the federal agencies for achieving these goals. . ~ e .~ ~7 ~ INTRODUCTION ~~r~ a Windthe motion of air relative to the earth's surfaceaffects a wide variety of human activities and can be both beneficial and harmful. One benefit, for example, has come with the evolution of wind-turbine technology, which has begun to make wind a viable energy source with the potential to contribute perhaps 10 percent of the nation's energy needs. Wind also plays an essential role in agriculture and silviculture, acting as a pollination agent for grain crops and several commercially valuable timber species. . c7 the focus of this analysis, however, is not on wind's benefits, but on the hazard resulting from extreme winds such as hurricanes and tornadoes. In this respect, the influence of near-surface winds is pervasive and increasing in scope as the global population and the built environment expand. Near-surface winds are the most variable of all meteorological elements, making their prediction and the control of their impacts all the more challenging. In the United States, the mean annual wind speed (for the contiguous 48 states) is ~ to 12 mph (4 to 6 m/s), but wind speeds of 50 mph (22 m/s) occur frequently throughout the country, and nearly every area occasionally experiences winds of 70 mph (31 m/s) or greater. In coastal areas of the East and Gulf coasts, tropical storms may bring wind speeds of well over 100 mph (45 m/s). WIND LOSSES: A PERSPECTIVE Many states in the United States are vulnerable to extreme weather, with hurricanes, tornadoes, severe thunderstorms, and downsIope winds inexorably exacting their tolls. Hurricane Hugo, which struck the Virgin Islands, Puerto Rico, and South Carolina in September 1989, caused more than 100 deaths and disrupted the lives of millions, inflicting over $4 billion in insured losses in the process. During the 35-year period from 1953 to 1989, tornadoes claimed 3550 lives-an average of 96 deaths per year. The May 22, 1

OCR for page 1
2 Wnd and He Built Environn~ent 1987, Saragosa, Texas, tornado, alone, caused 30 deaths, mostly of young children. Each year, the nation suffers several billion dollars in w~nd-related property and economic losses and assumes the direct costs of disaster relief and recovery efforts. The Federal Emergency Management Agent y (FEMA) alone has spent an average of nearly $400 minion per year for disaster relief during the past 20 years, with a significant portion of this used for wind- related events. From 1981 to 1990, the insurance industry spent nearly $23 billion on w~nd-related catastrophic events In the United States. Globally, w~ndstorm-related events cause an annual average of 30,000 deaths and many billions of dollars in direct losses (National Research Council, 1987~. United Nations statistics covering about 400 disasters since the beginning of the century indicate that roughly 15 percent of these events are windstorms, and lists of major disasters since the 1960s indicate that over half are due to extreme winds. LOOKING AHE~I) Worldwide, vulnerability to natural disasters is rising as a result of several factors, including rapid population growth concentrated in urban areas, especially along coastlines; increasing capital outlays for buildings and lifelines; deteriorating infrastructure systems; and growing interdependence among local, national, and global comunun~ties. These factors are particularly pertinent to the communities along the east coast of the United States. For example, national estimates of the population per mile of coastline suggest that by the year 2010 the population density on Florida's east and west coasts wall have increased about 130 percent from the 1988 level. Moreover, as the national population ages, an increasing percentage of coastal immigrants will probably be older individuals, a group more likely to inhabit manufactured houses, which are more vulnerable to extreme wind hazards. The Bureau of the Census estimates that by the year 2030, over 22 percent of the population will be 65 or older, compared with 12 percent in 1987. Millions of these individuals uric unda~hterilv make their `~, tr, the Sun Belt coastal states. _ . ^~ ~ J ~~_ ~_~4 ,~ ~~ TV ~~ Growing affluence, the development of attractive communities, good career opportunities, and the freedom of movement facilitated by low-cost transportation have resulted in the growth of residential and commercial construction in vulnerable, coastal regions. A 1989 study by the AD-hndust~y Research Advisory Council indicates that these construction activities resulted in a 64 percent increase in insured property exposures during the period 1980 to 1988. The combined structural value of these residential and commercial properties $~.86~trillion is a staggering indicator of the ~~tz~ctr~nhir Aama=^ potential. A ~~-_~ ok_ ^t _ ~e , . .. ~ . ~ ~ Cal ~ ~ ~^ ~~_ ~~ Baaing lo tne disaster potential is the gradual deterioration of many elements of the transportation infrastructure. For example, the compromise of critical transportation links, such as coastal bridges and overpasses essential

OCR for page 1
Executive Summary 3 to emergency evacuation and response, could measurably increase the vulnerability of the populations that these elements serve. Moreover, some climatologists predict increases in the frequency and seventy of intense Topical cyclones In the next few decades. It has been suggested that, given the multi-decadal cycle of West African precipitation and its apparent linkage to the weather cycle, an increased incidence of intense hurricanes in the United States during the 1990s and the early twenty- first century is likely. A combination of the above-mentioned factors would make ah communities in coastal regions more vulnerable to extreme wind hazards, including such cities as New Orieans, Tampa Bay, Miami, and others, which are particularly susceptible to mass inundation by storm surge because of the shape of their bays and coastlines. Nor wall inland areas be spared; these regions can also elect rising wind vuInerabili~though perhaps not to the extent expected for coastal areas-as structure density and value gradually increase. CREATING A NATIONAL WIND SCIENCE AND ENGINEERING PROGRAM Today, the sciences of meteorology and wind engineering are central to predicting and managing wind forces and their effects. Continued improvements in the ability to forecast severe weather have led to longer lead times tor responding to the disaster threat. ~ he application of w~nd- en~neenng principles to accommodate wind loads has become an unDortant , ~ ~ . , ~ . . ~ _ _ . aspect of modern construction practice. Research using modern boundary- layer wind tunnels and sophisticated computer modeling has greatly enhanced the designer's ability to ensure the safeW and comfort of structures for the least cost. Design provisions based more directly on wind-engineenng research than on traditional, empirical guidelines are also gradually finding their way into local building codes. In spite of these advances over the past 20 years, losses from w~nd- related hazards are mounting, particularly economic losses. The need for accelerated progress remains acute, especially in light of the expansion of the built environment and the rising exposure to w~nd-related events. Since the 1970s, the pace of this progress has faltered for lack of funding and the absence of a cohesive, national program of wind research and application. As indicated in the 1989 National Research Council report, Reducing Disasters' Toll, one major reason for the nation's inability to deal with mounting losses is that U.S. efforts in hazard mitigation have evolved slowly over many decades and are fragmented. Responsibility for these efforts is shared among federal, state, and local governments, as well as with the private sector, professional organizations, voluntary organizations, the insurance industry, and the public. This diffusion of responsibility stems from two factors. The first is the historic role in government reserved for states and localities. The second factor comes from the traditional perspective that views

OCR for page 1
4 Wnd and He Buill Environment natural hazards as acts of God for which little anticipatory action is possible and to which postdisaster human~tanan relief is the most important response as well as a much-public~zed noble cause. ~1L ~ _ ~ hi_ _ _ / ~ _ _ _ t ~ _1, ~ one nation s efforts in hazard management lack coordination and a coherent focus. At the federal level, for instance, the present research and implementation program reflects a piecemeal accumulation of activities initiated incrementally by Congress. Examples are the 1968 Flood Insurance Program and the 1977 National Earthquake Hazards Rein Program which address specific areas of concern. `'7- ~ 1_ _ _ ~ "^ , . . _ _ _ ~ . In. Id, wma-nazaro efforts are Spicy examples of the nation's inadequate and fragmented management capability, which is focused mostly on near-term and postdisaster activities. The United States as a whole spends no more than $4 million each year on w~nd-hazard mitigation, most of which is for storm warning capability (National Research Council, 1989~. Trough its National Weather Service, the National Oceanic and Atmospheric Administration is responsible for meeting the nation's needs in weather forecasting. It also conducts research relevant to hurricanes, tornadoes, floods, and droughts. The National Science Foundation, the nation's primary agency supporting science and engineering research, allocates no more than $750,000 each year to wind- engineering mitigation research. The FEMA's efforts are almost exclusively in disaster relief Other agencies, such as the Departments of Energy and Defense, which own and operate numerous facilities nationwide, often suffer significant damage from extreme wind events. Nonetheless, their support for the wind-engineering and wind-hazard research aimed al rein check ~ncc-~: is almost nonexistent. A 14~ ~1~ ~ ~~_.~_ _1 ~~, .~ ~ ~ e, ~,,_~_ ._ ^~nougn me National Weather Service is undergoing a slow, steady modernization program to advance its forecasting capabilities, the wind- engineenng discipline has suffered a period of stagnation, even disintegration, over the past decade. No U.S. organization is willing to spearhead the drive to advocate w~nd-hazard mitigation. From time to time-immediately following a major hurricane or tornad~a surge of interest stirs poli~nakers to debate what should be done in the future, but it withers rapidly because of the urgency of addressing the short-term needs of communities. The United States needs the political will to develop long-term goals and objectives to deal effectively with w~nd-ha~ard issues. The threat from extreme winds is real and dramatic for all Atlantic and Gulf coast states; for Hawaii, Puerto Rico, and the Virgin Islands; and for inland states as well. The nation's apparent indifference to this threat is astonishing and perplexing. How can this be rectified? Advocates must arise from within the affected communities, and they must be augmented by a strong voice from the professional community that addresses wind-hazard issues. Perhaps the Wind Engineenng Research Council could sense as this voice, in a role similar to that Played bv the Earthquake Engineering Research Institute for its constituents. ,~ ~ ~ -lnrougn these advocates' communities must then approach Congress to establish a National Wind Science and Engineering Program (NAWSEP).

OCR for page 1
Executive Summary 5 Such a program, which would provide the needed focus to address the nation's wind vulnerability, should include: . a coordinated program of wind research that draws upon expertise in both academia and industry, and addresses both structural and nonstructural mitigation measures; an outreach program to educate state and local governments on the nature of the wind risks they face, especially along vulnerable coastlines, and to transfer state-of-the-art wind mitigation measures, from improved building codes to computer-based expert systems that offer guidance In a variety of areas such as disaster preparation or structural design; a conscious effort to improve communication within the wind community and to foster renewed interest in this field through undergraduate and graduate curriculum development and through support for graduate study; and . a commitment to international cooperation in w~nd-eng~neering work through the support of selected, joint studies with other nation.c .ch~rins, similar w~nd-haz~rd and engineering concerns. . _ ~ ~ Once the concept of a NAWSEP is accepted, the process of formulating its specific structure may benefit from the convening of one or more national workshops to arrive at appropriate working agendas for wind research and for mitigation and outreach activities to be undertaken as part of the NAWSEP. Chapter ~ of this report provides an overview of wades impact on the built environment. It is followed by detailed presentations of the issues critical to the establishment of a sound and long-term national wind program. Chapter 7 then summarizes the panel's key conclusions and recommendations concerning the critical issues that have been identified.