NAE Website - Highway Design and Construction: The Innovation Challenge. Innovations and advances in research are changing the way highways are built in America. The Egyptians were pouring concrete in 2. BC, and the Romans used it to construct the Pantheon and the Colosseum. By the mid- 1. 80. Europeans were building bridges with concrete, and the first “modern” concrete highway pavements appeared in the latter part of the 1. Naturally occurring asphalts, which have been used for waterproofing for thousands of years, came into common use in road construction in the 1. The first iron bridge was constructed in 1. These materials—concrete, asphalt, and steel—are now the mainstays of highway and bridge construction throughout the world, as well as of most types of public works infrastructure. Concrete and steel, the most versatile of these materials, are used for bridges and other highway structures; concrete and asphalt are used for roadway pavements. Everyone is familiar with concrete, asphalt, and steel, and some of us have worked with them, perhaps on home improvement projects. This familiarity, coupled with the long history of their many uses, has led many otherwise technically savvy people to believe that these materials are well understood, that their performance can be easily and reliably predicted, and that the technical challenges in using them for highways were overcome long ago. However, such notions are largely incorrect and misleading. For example, consider concrete, which is a mixture of portland cement, sand, aggregate (gravel or crushed stone), and water. Its performance characteristics are determined by the proportions and characteristics of the components, as well as by how it is mixed and formed. The underlying chemical reactions of concrete are surprisingly complex, not completely understood, and vary with the type of stone. Steel may be added for tensile strength (reinforced concrete), and a variety of additives have been identified to improve the workability and performance of concrete in particular applications and conditions. Damage and deterioration to concrete can result from excessive loadings and environmental conditions, such as freeze- thaw cycles and chemical reactions with salts used for deicing. Worldwide, concrete construction annually consumes about 1. M. S. Given transportation costs, there is a huge financial incentive to using local sources of stone, even if the properties of that stone are less than ideal. Thus concrete is not a homogenous material. In truth, an unlimited number of combinations and permutations are possible. Much the same can be said of asphalt—technically, asphaltic concrete—which is also a mixture of aggregate (gravel or crushed stone), sand, and cement (asphalt binder); economics promote the use of locally available materials; and the underlying chemistry is not well understood. The characteristics of asphalt binder, for instance, vary depending on the source of crude oil from which it is derived. The metallurgy of steel is probably better understood than the chemistry of either asphalt or concrete, but it too is a mixture with virtually limitless combinations. Strength, toughness, corrosion resistance, and weldability are some of the performance characteristics that vary with the type of steel alloy used and the intended applications. As uses evolve and economic conditions change, we have a continuing need for a more sophisticated understanding of these common materials. Even though they are “mature” products, there is still room for significant incremental improvements in their performance. Because fundamental knowledge is still wanting, there is also considerable potential for breakthroughs in their performance. Factors That Affect Highway Construction. All other things being equal, stronger, longer lasting, less costly highway materials are desirable and, given the quantities involved, there are plenty of incentives for innovation. Road Design Susan Handy TTP Orientation Seminar. Riverfront Parkway and Downtown Streets. In highway transportation, however, all other things are not equal. A number of other factors contribute to the urgent and continuing need for innovation. First, traffic volume and loadings continue to increase. The 4. 7,0. 00- mile interstate highway system today carries more traffic than the entire U. S. Department of Transportation (DOT) estimates that in metropolitan areas the annual cost of traffic congestion for businesses and citizens is nearly $1. PB Consult, Inc., 2. On rural interstates, overall traffic more than doubled between 1. Our overstressed highway system is not very resilient. Thus disruptions of any sort, such as lane and roadway closings, especially in major metropolitan areas and on key Interstate routes, can cause massive traffic snarls. This means that repair and reconstruction operations must often be done at night, which introduces a variety of additional complexities and safety issues. Occasionally, heroic measures must be taken to keep traffic moving during construction. Chapter 2 Highway Design Standards Flexibility PDF Chapter 2 Highway Design Standards Flexibility.pdf DOWNLOAD HERE CHAPTER 2 HIGHWAY DESIGN STANDARDS FLEXIBILITY godwin pumps cd150 service manual pdfsdocuments com, godwin. Flexible Design of New Jersey’s Main Streets prepared by the Voorhees Transportation Policy Institute Edward J. Bloustein School of Planning & Public Policy Rutgers, The State University of New Jersey for the New Jersey. Flexibility in Highway Design Chapter 3. Highway Design Features, Volume I, Access Control, FHWA. 302 p., 9,953 KB (PDF) Subject: Highway design, Context sensitive design, Environmental design, Landscape design. Keywords: Context sensitive design, design flexibility, CSD, CSS, design trade off. The Department's Highway Design Manual, Federal Highway Administration (FHWA) regulations, FHWA's Flexibility in Highway Design publication, and the American. Design Flexibility in Massachusetts MassHighway Project Development and Design GuideMassHighway Project Development and Design Guide Minnesota DOT Flexible Design for 21stst Century Challenges: Century Challenges: Balancing.For example, during construction of the “Big Dig” in Boston, the elevated Central Artery was in continuous service while cut- cover tunnels were constructed directly below it. Third, environmental, community, and safety requirements have become more stringent. For many good reasons, expectations of what a highway should be, how it should operate, and how it should interact with the environment and adjacent communities are constantly evolving. Designs to promote safety, measures to mitigate a growing list of environmental impacts, and attention to aesthetics have fundamentally changed the scope of major highway projects in the United States. For example, on Maryland’s $2. Intercounty Connector project in suburban Washington, D. C., which is now under construction, environmental mitigation accounts for 1. AASHTO, 2. 00. 8). Fourth, costs continue to rise. Building and maintaining highways cost effectively is an ever- present goal of good engineering. But cost increases in highway construction have been extraordinary due in part to the expanded scope of highway projects and construction in demanding settings. In addition, the costs of the mainstay materials—portland cement, asphalt binder, and steel—have risen dramatically as the world, particularly China, has gone on a construction binge. The Federal Highway Administration’s cost indices for portland cement concrete pavement, asphalt pavement, and structural steel increased by 5. FHWA, 2. 00. 6). Fortunately, research and innovation in construction have never stopped, although they are not always sufficiently funded and they seem to fly beneath the radar of many scientists and engineers. Nevertheless, there have been great successes, which are cumulatively changing how highways are built in America. The Superpave Design System. In response to widespread concerns about premature failures of hot- mix asphalt pavements in the early 1. The seven- year Strategic Highway Research Program (SHRP), which was managed by the National Research Council, developed a new system of standard specifications, test methods, and engineering practices for the selection of materials and the mix proportions for hot- mix asphalt pavement. The new system has improved matches between combinations of asphalt binder and crushed stone and the climatic and traffic conditions on specific highways. State departments of transportation (DOTs) spend more than $1. TRB, 2. 00. 1). SHRP rolled out the Superpave system in 1. Each state DOT had to be convinced that the benefits would outweigh the modest additional costs of Superpave mixes, as well as the time and effort to train its staff and acquire necessary equipment. FIGURE 1 - Superpave application on Michigan State Route 9. Iron Mountain. The Superpave system, which matches the combinations of asphalt binder and crushed stone to the climatic and traffic conditions on specific highways, was developed under the National Research Council–managed Strategic Highway Research Program and is in use in every state. Michael.)A survey in 2. DOTs (including the District of Columbia and Puerto Rico) were using Superpave (Figure 1). The remaining two states indicated that they would be doing so by the end of 2. Throughout the implementation period, researchers continued to refine the system (e. A 1. 99. 7 study by the Texas Transportation Institute projected that, when fully implemented, Superpave’s annualized net savings over 2. Little et al., 1. Moreover, analyses by individual states and cities have found that Superpave has dramatically improved performance with little or no increase in cost. Superpave is not only an example of a successful research program. It also demonstrates that a vigorous, sustained technology- transfer effort is often required for innovation in a decentralized sector, such as highway transportation. FIGURE 2 - Aerial view of the east span of the San Francisco- Oakland Bay Bridge, Labor Day 2. Demolishing the old viaduct sections and moving the prefabricated section into place was accomplished in 7. But the need for reconstructing or replacing heavily used highway facilities has increased the use of prefabricated components in startling ways. In some cases components are manufactured thousands of miles from the job site; in others, they are manufactured immediately adjacent to the site. Either way, we are rethinking how design and construction can be integrated. When the Texas Department of Transportation needed to replace 1. Houston, it found that the existing columns were reusable, but the bent caps (the horizontal connections between columns) had to be replaced. As an alternative to the conventional, time- consuming, cast- in- place approach, researchers at the University of Texas devised new methods of installing precast concrete bents. In this project, the precast bents cut construction time from 1. TRB, 2. 00. 1). As part of a massive project to replace the San Francisco- Oakland Bay Bridge, the California Department of Transportation and the Bay Area Toll Authority had to replace a 3. Yerba Buena Island.
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