Click for next page ( 136


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 135
Intro~action MILTON PIKARSKY The political, economic, and social consequences of the Organization of Petroleum Exporting Countries' (OPEC's) actions during the late 1973-1974 period, exacerbated by the Iranian embargo in 1979, are still reverberating, and the world's transportation systems including that of the United States are in a major transitional period. The U.S. transportation system can be briefly described as a vast enterprise, the costs of which account for about $500 billion, or in excess of 20 percent of the gross national product, smaller than the amount for housing and larger than the amount for food. It is a fragmented system built and operated by thousands of private firms and government agencies in a decentralized fashion. Relatively few decisions are made, and few individuals or entities have effective control or even influence over much of the system. Rather, the relative size and efficiencies of different subsystems are the product of thousands of lower-level actions that respond to market decisions of shippers and travelers. All of this, when aggregated, results in the total transportation system. The current technological systems supporting this vast transportation network reflect nearly 100 years of progress, much of which has occurred in the last 50 years. Today, increasingly, technological innovation must be responsive to social, economic, and political pressures if it is to be effective. The three papers that follow explore current technological develop- ments and trends in these areas of transportation: (l) aviation and aircraft technology, (2) use of reinforced earth in surface transportation projects, and (3) railroad technology. 135

OCR for page 135
136 TRANSPORTATION TECHNOLOGY The U.S. civil aviation industry has been the dominant technological and market force. However, competitive forces worldwide, the domestic economy, and market uncertainties may alter the shape of the industry in the coming years. Technologically the civil aircraft vehicle is highly efficient because of its advanced electronic systems, and increased tech- nological efficiency is possible. However, affordability and planning imply restraint. It is against this background that the industry must shape itself in the future, and in the first paper, John E. Steiner describes the current technology as well as the technological building blocks and the potential rewards and challenges ahead. In the next paper, James K. Mitchell discusses the cutting edge of technology with regard to soil, one of our most abundant and least expensive potential construction materials. Human attempts to improve the soil for use as a structural material precede recorded history. Indeed, they can be dated to engineering and construction projects of 5,000 years ago, when the pyramids of the shenzi on the Tibetan-Mongolian plateau were built of a compacted mixture of clay and lime. We are all familiar with the Roman-built roads, which outlasted the empire and are still in evidence today. Soils have been wetted, dried, heated, frozen, pounded upon, vibrated, mixed with other materials, pushed, rolled, implanted with things, and dehydrated to improve their properties. Principles of soil behavior and foundation engineering that are still valid today were recorded in the Tribiuses, 10 books of archi- tecture of the first century B.C. In the New World the Mayans constructed roads that had a base of broken limestone with stone sizes decreasing upward, covered with a mortar of lime and sifted earth. The scarcity of timber in the southwestern United States and regions of Central and South America led to exploitation of local stones and soils, resulting in the familiar adobe brick, strengthened as necessary with sticks and reeds. The quest to better adapt soils for use in construction is not surprising, since in addition to being one of our most abundant and least expensive materials, soil is also one of our potentially most useful structural ma- terials. Despite the known potential to facilitate earth work and soil improve- ment work on a large scale, little exploitation of this potential construc- tion material occurred until the twentieth century. Indeed only in the last two decades have the methodologies for soil improvement and ground strengthening been developed. Of the existing methodologies, soil re- inforcement is the one most intensely studied and advanced in appli- cation. Many of the currently available techniques were specifically de- veloped for use in highway construction. Dr. Mitchell's presentation considers the currently available types of soil reinforcement, their ap- plication, design, construction, and economies.

OCR for page 135
INTRODUCTION 137 In the third paper, William J. Harris, Jr., discusses technological opportunities in the railroad industry. Successes stemming from earlier technological developments led the industry to a preeminent competitive position. It is natural that under those circumstances the railroads have failed to pursue new technology. However, with the gradual develop- ment of the truck and waterway modes of transportation and the com- pletion of the interstate system of highways, the railroads were suddenly confronted by a vigorous economic challenge. The railroad industry has responded with the adoption of new tech- nologies to force safety improvements and efficiencies in rail transpor- tation. Dr. Harris describes the current status of technology and the anticipated trends in the industry, bringing to the discussion his unique awareness of the technological and research issues facing the railroads during the present, uncertain, transition period on which deregulation legislation has had an impact.