986 resultados para Road construction contracts.


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With the support of the Iowa Fly Ash Affiliates, research on reclaimed fly ash for use as a construction material has been ongoing since 1991. The material exhibits engineering properties similar to those of soft limestone or sandstone and a lightweight aggregate. It is unique in that it is rich in calcium, silica, and aluminum and exhibits pozzolanic properties (i.e. gains strength over time) when used untreated or when a calcium activator is added. Reclaimed Class C fly ashes have been successfully used as a base material on a variety of construction projects in southern and western Iowa. A pavement design guide has been developed with the support of the Iowa Fly Ash Affiliates. Soils in Iowa generally rate fair to poor as subgrade soils for paving projects. This is especially true in the southern quarter of the state and for many areas of eastern and western Iowa. Many of the soil types encountered for highway projects are unsuitable soils under the current Iowa DOT specifications. The bulk of the remaining soils are Class 10 soils. Select soils for use directly under the pavement are often difficult to find on a project, and in many instances are economically unavailable. This was the case for a 4.43-mile grading (STP-S- 90(22)-SE-90) and paving project in Wapello County. The project begins at the Alliant Utilities generating station in Chillicothe, Iowa, and runs west to the Monroe-Wapello county line. This road carries a significant amount of truck traffic hauling coal from the generating station to the Cargill corn processing plant in Eddyville, Iowa. The proposed 10-inch Portland Cement Concrete (PCC) pavement was for construction directly on a Class 10 soil subgrade, which is not a desirable condition if other alternatives are available. Wapello County Engineer Wendell Folkerts supported the use of reclaimed fly ash for a portion of the project. Construction of about three miles of the project was accomplished using 10 inches of reclaimed fly ash as a select fill beneath the PCC slab. The remaining mile was constructed according to the original design to be used as a control section for performance monitoring. The project was graded during the summers of 1998 and 1999. Paving was completed in the fall of 1999. This report presents the results of design considerations and laboratory and field testing results during construction. Recommendations for use of reclaimed fly ash as a select fill are also presented.

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For most people, highway engineering, design and right of way acquisition are not of immediate concern. However, when you own or rent property that will be affected by highway construction, you begin to consider road building from a different and personal viewpoint. Right of way is the land on which highways are built. The amount of land needed depends on the engineering standards that must be met for the type of highway that will be built or improved. This booklet will acquaint property owners, tenants and the public with the procedures the Iowa Department of Transportation follows in acquiring right of way for a highway. It is not a source of technical definitions or legal advice. Further, it is not intended to establish a legal standard.

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The Quadrennial Needs Study was developed to assist in the identification of highway needs and the distribution of road funds in Iowa among the various highway entities. During the period 1978 to 1990, the process has seen large shifts in needs and associated funding distribution in individual counties with no apparent reasons. This study investigated the reasons for such shifts. The study identified program inputs that can result in major shifts in needs either up or down from minor changes in the input values. The areas of concern were identified as the condition ratings for roads and structures, traffic volume and mix counts, and the assignment of construction cost areas. Eight counties exhibiting the large shifts (greater than 30%) in needs over time were used to test the sensitivity of the variables. A ninth county was used as the base line for the study. Recommendations are identified for improvements in the process of data collection in the areas of road and structure condition--rating, traffic, and in the assignment of construction cost areas. Advice is also offered in how to account for changes in jurisdiction between successive studies. Maintenance cost area assignment and levels of maintenance service are identified as requiring additional detailed research.

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Recent reports have indicated that 23.5 percent of the nation's highway bridges are structurally deficient and 17.7 percent are functionally obsolete. A significant number of these bridges are on the Iowa county road system. The objective of the investigation described in this report was to identify, review and evaluate replacement bridges currently being used by various counties in Iowa and surrounding states. Iowa county engineers, county engineers in neighboring states as well as private manufacturers of bridge components, and regional precad prestressed concrete manufacturers were contacted to determine the most common replacement bridge types being used. Depending upon the findings of the review, possible improvements and/or new replacement bridge systems were to be proposed. A questionnaire was developed and sent to county engineers in Iowa and several counties in surrounding states. The results of the questionnaire showed that the most common replacement bridges in Iowa are the continuous concrete slab and prestressed concrete bridges. The primary reason these types are used is because of the availability of standard designs and because of their ease of maintenance. Counties seldom construct these types of bridges using their own labor forces, but instead contract the work. However, county forces are used to construct steel stringer, precast reinforced concrete and timber bridges. In general, 69 percent of the counties indicate an ability and willingness to use their own forces to design and construct relatively short span bridges (i.e., 40 A or less) provided the construction procedures are relatively simple. Several unique replacement bridge types used in Iowa that are constructed by county forces are documented and presented in this report. Sufficient details are provided to allow county engineers to determine if some of these bridges could be used to resolve some of their own replacement bridge problems. Where possible, cost information has also been provided. Each of these bridge types were evaluated for various criteria (e.g., cost effectiveness, conformance to AASI-ITO standards, range of sizes, etc.) by a panel of four Iowa county engineers; a summary of this critique is included. After evaluating the questionnaire responses from the counties and evaluating the various bridge replacement concepts currently in use, one new bridge replacement concept and one modification of a current Iowa county bridge replacement concept were developed. Both of these concepts would utilize county labor forces.

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This phase of the electronic collaboration project involved two major efforts: 1) implementation of AEC Sync (formerly known as Attolist), a web-based project management system (WPMS), on the Broadway Viaduct Bridge Project and the Iowa Falls Arch Bridge Project and 2) development of a web-based project management system for bridge and highway construction projects with less than $10 million in contract value. During the previous phase of this project (fiscal year 2010), the research team helped with the implementation process for AEC Sync and collected feedback from the Broadway Viaduct project team members before the start of the project. During the 2011 fiscal year, the research team collected the post-project surveys from the Broadway Viaduct project members and compared them to the pre-project survey results. The results of the AEC Sync implementation on the Broadway project were positive. The project members were satisfied with the performance of the AEC Sync software and how it facilitated document management and its transparency. In addition, the research team distributed, collected, and analyzed the pre-project surveys for the Iowa Falls Arch Bridge Project. The implementation of AEC Sync for the Iowa Falls Arch Bridge Project appears to also be positive, based on the pre-project surveys. The fourth phase of this electronic collaboration project involves the identification and implementation of a WPMS solution for smaller bridge and highway projects. The workflow for the shop drawing approval process for sign truss projects was documented and used to identify possible WPMS solutions. After testing and evaluating several WPMS solutions, Microsoft SharePoint Foundation’s site pages were selected to be pilot-tested on sign truss projects. Due to the limitation on the SharePoint license that the Iowa Department of Transportation (DOT) has, a file transfer protocol (FTP) site will be developed alongside this site to allow contractors to upload shop drawings to the Iowa DOT. The SharePoint site pages are expected to be ready for implementation during the 2012 calendar year.

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Sustainable Concrete Pavements: A Manual of Practice is a product of the National Concrete Pavement Technology Center at Iowa State University’s Institute for Transportation, with funding from the Federal Highway Administration (DTFH61-06-H-00011, Work Plan 23). Developed as a more detailed follow-up to a 2009 briefing document, Building Sustainable Pavement with Concrete, this guide provides a clear, concise, and cohesive discussion of pavement sustainability concepts and of recommended practices for maximizing the sustainability of concrete pavements. The intended audience includes decision makers and practitioners in both owner-agencies and supply, manufacturing, consulting, and contractor businesses. Readers will find individual chapters with the most recent technical information and best practices related to concrete pavement design, materials, construction, use/operations, renewal, and recycling. In addition, they will find chapters addressing issues specific to pavement sustainability in the urban environment and to the evaluation of pavement sustainability. Development of this guide satisfies a critical need identified in the Sustainability Track (Track 12) of the Long-Term Plan for Concrete Pavement Research and Technology (CP Road Map). The CP Road Map is a national research plan jointly developed by the concrete pavement stakeholder community, including Federal Highway Administration, academic institutions, state departments of transportation, and concrete pavement–related industries. It outlines 12 tracks of priority research needs related to concrete pavements. CP Road Map publications and other operations support services are provided by the National Concrete Pavement Technology Center at Iowa State University. For details about the CP Road Map, see www.cproadmap. org/index.cfm.

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The film depicts period traffic congestion, sharp and winding sections of road, steep hills making trucks slow to a crawl, and dangerous vehicle and pedestrian crossings, all important reasons why highway design and safety improvements, and highway relocation were needed. In fact, when the film was produced, U.S. 30 or the Lincoln Highway was the busiest primary road in Iowa; and the section between State Center and Boone was deemed “critical,” meaning it was considered dangerous by the ISHC’s Efficiency Standards.

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The possibility of local elastic instabilities is considered in a first¿order structural phase transition, typically a thermoelastic martensitic transformation, with associated interfacial and volumic strain energy. They appear, for instance, as the result of shape change accommodation by simultaneous growth of different crystallographic variants. The treatment is phenomenological and deals with growth in both thermoelastic equilibrium and in nonequilibrium conditions produced by the elastic instability. Scaling of the transformed fraction curves against temperature is predicted only in the case of purely thermoelastic growth. The role of the transformation latent heat on the relaxation kinetics is also considered, and it is shown that it tends to increase the characteristic relaxation times as adiabatic conditions are approached, by keeping the system closer to a constant temperature. The analysis also reveals that the energy dissipated in the relaxation process has a double origin: release of elastic energy Wi and entropy production Si. The latter is shown to depend on both temperature rate and thermal conduction in the system.

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Apamè, Stratonice et Laodice(s) sont les différents protagonistes de cette thèse qui s'attache à saisir comment les souveraines séleucides participent au pouvoir. Principalement centré sur les identités politiques des reines que l'épigraphie grecque et akkadienne nous permet de re-construire, ce travail se développe chronologiquement. Il débute en 324, lors des noces Suse - qui virent Séleucos épouser la bactrienne Apamè, pour se terminer en 177 par la mention de la reine Laodice, la mère du roi Séleucos IV. Nous avons, par ce travail, démontré que les reines séleucides participent pleinement au pouvoir et ce dès le début de la constitution du royaume. Les souveraines mobilisent l'administration, écrivent aux cités, possèdent une autonomie financière grâce aux domaines qu'elles détiennent et disposent de réseaux d'influence personnels. Les identités qu'elles se construisent les lient notamment à la fécondité et leur permettent d'avoir un domaine d'action politique particulier inaccessible au roi. Elles sont en ce sens des partenaires politiques indispensables qui soutiennent à la fois la perpétuation du pouvoir royal et le maintien du territoire séleucide. Si par ce travail nous avons focalisé notre attention sur les basilissai, le cas de la première épouse d'Antiochos II nous a permis de mettre en évidence la polygamie des souverains, l'organisation « hiérarchique » des différentes épouses du roi ainsi que les stratégies développées par le pouvoir séleucide pour désigner celle dont sera issus le successeur. Enfin, le pouvoir séleucide, tel que nous l'avons décrit, ne permet plus de défendre les hypothèses de répudiation ou de régence des souveraines séleucides avancées pour les cas des épouses d'Antiochos II et d'Antiochos III.

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In this paper we study the role of incomplete ex ante contracts for ex post trade. Previous experimental evidence indicates that a contract provides a reference point for entitlements when the terms are negotiated in a competitive market. We show that this finding no longer holds when the terms are determined in a non-competitive way. Our results imply that the presence of a "fundamental transformation" (i.e., the transition from a competitive market to a bilateral relationship) is important for a contract to become a reference point. To the best of our knowledge this behavioral aspect of the fundamental transformation has not been shown before.

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The Rebuild Iowa Office (RIO) continues to coordinate the state‘s recovery effort from the storms, tornadoes and floods of 2008. Much has been accomplished since the Office‘s last quarterly report was issued in July 2010. State funding has been disbursed to help Iowans with unmet needs and housing. Local governments and entities are utilizing millions of federal dollars so thousands of disaster-impacted homeowners can be offered a buyout. More infrastructure projects are under construction and new neighborhoods are being built with mitigation efforts in mind. However, as Iowa continues to celebrate many successes along the road to recovery, it must also address the numerous challenges that are encountered along the path. Recovering from the state‘s largest disaster must be looked at as a marathon, not a sprint. Over the past three months, the RIO has especially remained focused on helping small business owners impacted by the 2008 disasters. Many disaster-affected businesses have reopened their doors, however their debt load continues to be overwhelming and many still struggle with the timeliness of the disbursement of funds. This report describes how programs and recent modifications are working to assist recovering businesses. This report contains updates on housing progress while outlining the complexities behind certain programs and the bottlenecks communities are facing due to strict federal guidelines for implementation. This following pages also describe how Iowa is implementing Smart Planning principles, publicizing flood awareness through outreach efforts and preparing a blueprint for the state to follow when future disasters occur. As always, the RIO recognizes and thanks the countless leaders and front-line workers from local, regional, state and federal government, businesses, non-profit organizations and private citizens that have provided input, support and leadership. Their dedication to Iowa‘s disaster recovery has made the plans and projects on the following pages possible.

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General principles • Everyone at the construction site, particularly foremen and supervisors, is responsible for recognizing and troubleshooting potential problems as they arise. • Batches of concrete should be consistent and uniformly mixed. • A major cause of pavement failure is unstable subgrade. The subgrade should consist of uniform material, and the subgrade system must drain well. • Dowel bars are important for load transfer at transverse joints on pavements with high truck volumes. Dowels must be carefully aligned, horizontally and vertically, to prevent pavement damage at the joints. • Stringlines control the slipform paver’s horizontal and vertical movement and ensure a smooth pavement profile. Once stringlines are set, they should be checked often and not disturbed. • Overfinishing the new pavement and/or adding water to the surface can lead to pavement surface problems. If the concrete isn’t sufficiently workable, crews should contact the project manager. Changes to the mixture or to paver equipment may reduce the problem. • Proper curing is critical to preventing pavement damage from rapid moisture loss at the pavement surface. • A well spaced and constructed system of joints is critical to prevent random cracking. • Joints are simply controlled cracks. They must be sawed during the brief time after the pavement has gained enough strength to prevent raveling but before it begins to crack randomly (the “sawing window”). • Seasonal and daily weather variations affect setting time and other variables in new concrete. Construction operations should be adjusted appropriately.