931 resultados para highway operating contracts
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National Highway Traffic Safety Administration, Washington, D.C.
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Mode of access: Internet.
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Federal Highway Administration, Office of Implementation, McLean, Va
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Mode of access: Internet.
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Mode of access: Internet.
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Performance-based maintenance contracts differ significantly from material and method-based contracts that have been traditionally used to maintain roads. Road agencies around the world have moved towards a performance-based contract approach because it offers several advantages like cost saving, better budgeting certainty, better customer satisfaction with better road services and conditions. Payments for the maintenance of road are explicitly linked to the contractor successfully meeting certain clearly defined minimum performance indicators in these contracts. Quantitative evaluation of the cost of performance-based contracts has several difficulties due to the complexity of the pavement deterioration process. Based on a probabilistic analysis of failures of achieving multiple performance criteria over the length of the contract period, an effort has been made to develop a model that is capable of estimating the cost of these performance-based contracts. One of the essential functions of such model is to predict performance of the pavement as accurately as possible. Prediction of future degradation of pavement is done using Markov Chain Process, which requires estimating transition probabilities from previous deterioration rate for similar pavements. Transition probabilities were derived using historical pavement condition rating data, both for predicting pavement deterioration when there is no maintenance, and for predicting pavement improvement when maintenance activities are performed. A methodological framework has been developed to estimate the cost of maintaining road based on multiple performance criteria such as crack, rut and, roughness. The application of the developed model has been demonstrated via a real case study of Miami Dade Expressways (MDX) using pavement condition rating data from Florida Department of Transportation (FDOT) for a typical performance-based asphalt pavement maintenance contract. Results indicated that the pavement performance model developed could predict the pavement deterioration quite accurately. Sensitivity analysis performed shows that the model is very responsive to even slight changes in pavement deterioration rate and performance constraints. It is expected that the use of this model will assist the highway agencies and contractors in arriving at a fair contract value for executing long term performance-based pavement maintenance works.
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The 10th Parallel marine and aerial routes linking South America and West Africa harbor a long history of trade between the two continents. More recently, these routes have become one of the preferred routes used by Latin American traffickers for shipping multi-tons of cocaine destined for the growing European market. The Parallel’s growing importance in cocaine trafficking has made it known as cocaine “Highway 10” among law enforcement. Latin American cocaine trafficking organizations, particularly the Colombian ones, have established stable bases in West Africa, controlling and developing the route. West African facilitators, Nigerians as well as an increasing number of nationals from all countries where shipments are stocked, have developed a stronger capacity for taking over more ambitious and lucrative role in the business as transporters, partners, and final buyers. In one case (Guinea), the West African partner had already started developing his own trafficking and manufacturing capacity, reproducing the patterns that made Colombia the business model of the drug industry. In this reshaped context, of particular concern is the role played by the Colombian FARC (Fuerzas Armadas Revolucionarias de Colombia) as provider of cocaine shipments to West African cocaine entrepreneurs, as well as the impact of drug trafficking money on the financing of terrorist and rebel groups operating in the Sahel-Saharan belt.
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Performance-based maintenance contracts differ significantly from material and method-based contracts that have been traditionally used to maintain roads. Road agencies around the world have moved towards a performance-based contract approach because it offers several advantages like cost saving, better budgeting certainty, better customer satisfaction with better road services and conditions. Payments for the maintenance of road are explicitly linked to the contractor successfully meeting certain clearly defined minimum performance indicators in these contracts. Quantitative evaluation of the cost of performance-based contracts has several difficulties due to the complexity of the pavement deterioration process. Based on a probabilistic analysis of failures of achieving multiple performance criteria over the length of the contract period, an effort has been made to develop a model that is capable of estimating the cost of these performance-based contracts. One of the essential functions of such model is to predict performance of the pavement as accurately as possible. Prediction of future degradation of pavement is done using Markov Chain Process, which requires estimating transition probabilities from previous deterioration rate for similar pavements. Transition probabilities were derived using historical pavement condition rating data, both for predicting pavement deterioration when there is no maintenance, and for predicting pavement improvement when maintenance activities are performed. A methodological framework has been developed to estimate the cost of maintaining road based on multiple performance criteria such as crack, rut and, roughness. The application of the developed model has been demonstrated via a real case study of Miami Dade Expressways (MDX) using pavement condition rating data from Florida Department of Transportation (FDOT) for a typical performance-based asphalt pavement maintenance contract. Results indicated that the pavement performance model developed could predict the pavement deterioration quite accurately. Sensitivity analysis performed shows that the model is very responsive to even slight changes in pavement deterioration rate and performance constraints. It is expected that the use of this model will assist the highway agencies and contractors in arriving at a fair contract value for executing long term performance-based pavement maintenance works.
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(a) Iowa has a total of 101,620 miles of rural roads, both primary and secondary. (b) On January 1, 1951, a total of 68,869 miles of these rural roads were surfaced - mostly with gravel and crushed stone. (c) Additional roads are being surfaced at the rate of 2676 miles per year. (d) Iowa's highway program provides for a surfaced road to every reasonably located rural home and a paved or other type of dustless surface on all primary roads. (e) Iowa's highway funds come 26.0 per cent from property taxes, 63.5 per cent from road use taxes, 10.5 per cent from Federal aid. (f) Annual income under present laws, available for highway construction, is approximately For primary roads ----------------- $24,000,000 For secondary roads---------------- $41,967,000 (g) Iowa's highway improvements are being paid for as built. No new bonds are being issued. (h) Unobligated available farm to market road funds are rapidly being placed under contract. (i) The letting of highway contracts is increasing rapidly. (j)- Iowa's highway program is estimated to cost $945,000,000 and will require twenty years to build. These are the highlights of Iowa's highway program. The details will follow in succeeding paragraphs.
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History has shown that projects move in and out of poor status through the life of the project. Predicting the success or failure of a project to complete on time because of its recent history on the contract status report could provide our project managers another tool for monitoring contract progress. In many instances, poor contract progress results in the loss of contract time and late completion of projects. This research evaluates the combinations of work type, point in time physical work begins, recent poor status, and contract bid amount as indicators of late project completion.
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The South Carolina Department of Transportation routinely retains Professional Consulting Engineering firms to provide engineering design and related professional services for the preparation of construction plans or design-build Request for Proposal bid packages for a wide variety of Federal-aid Highway Program roadway and bridge construction projects throughout South Carolina.The purpose of this project is to examine the current process of determining a "Fair and Reasonable" fixed fee for professional service contracts and to evaluate possible alternative methods including practices in other states that may improve the process, particularly in light of the considerable variation in audited overhead rates among consulting firms. In reviewing such alternative methods particular attention will be given to evaluating the potential impact of the method as an incentive to consulting firms to effectively manage their overhead costs.
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This paper aims to discuss the role of foreign merchants, operating from Portugal, in the Portuguese overseas trade, during the first ten years of Iberian Union. The focus is not in products or routes, but in the mechanisms of association of such merchants. Iberian Union created a legal framework which prohibited the interference and trade of Portuguese agents in the Spanish Empire and vice-versa. Due to the imperialist wars of the Habsburgs, the Portuguese Empire also suffered from Dutch and English rivalry both in the Indic and in the Atlantic and also from the embargos of Dutch and English products and ships in Iberian ports. In such conjuncture, how did merchants related with each other? What was the impact of the political union of the Portuguese and Spanish crowns in trading associations? The used data sources are the notarial contracts of Lisbon for the same period. The paper highlights the role of Castilian merchants in the Portuguese trade, but it also stresses that Iberian partnerships have prevailed before 1580. The role of other merchants, such as Flemish/Dutch, Germans, Italians and French, is also considered. The paper discusses how and why did these merchants join in trans-national partnerships and what was their role in the Portuguese trade network at the time.
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A phase shift proximity printing lithographic mask is designed, manufactured and tested. Its design is based on a Fresnel computer-generated hologram, employing the scalar diffraction theory. The obtained amplitude and phase distributions were mapped into discrete levels. In addition, a coding scheme using sub-cells structure was employed in order to increase the number of discrete levels, thus increasing the degree of freedom in the resulting mask. The mask is fabricated on a fused silica substrate and an amorphous hydrogenated carbon (a:C-H) thin film which act as amplitude modulation agent. The lithographic image is projected onto a resist coated silicon wafer, placed at a distance of 50 mu m behind the mask. The results show a improvement of the achieved resolution - linewidth as good as 1.5 mu m - what is impossible to obtain with traditional binary masks in proximity printing mode. Such achieved dimensions can be used in the fabrication of MEMS and MOEMS devices. These results are obtained with a UV laser but also with a small arc lamp light source exploring the partial coherence of this source. (C) 2010 Optical Society of America
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We report on a simple and accurate method for determination of thermo-optical and spectroscopic parameters (thermal diffusivity, temperature coefficient of the optical path length change, pump and fluorescence quantum efficiencies, thermal loading, thermal lens focal length, etc) of relevance in the thermal lensing of end-pumped neodymium lasers operating at 1.06- and 1.3-mu m channels. The comparison between thermal lensing observed in presence and absence of laser oscillation has been used to elucidate and evaluate the contribution of quantum efficiency and excited sate absorption processes to the thermal loading of Nd: YAG lasers. (c) 2008 Optical Society of America.
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We theoretically investigate spin-polarized transport in a system composed of a ferromagnetic scanning-tunneling-microscope (STM) tip coupled to an adsorbed atom (adatom) on a host surface. Electrons can tunnel directly from the tip to the surface or via the adatom. Since the tip is ferromagnetic and the host surface (metal or semiconductor) is nonmagnetic we obtain a spin-diode effect when the adatom is in the regime of single occupancy. This effect leads to an unpolarized current for direct bias (V > 0) and polarized current for reverse (V < 0) bias voltages, if the tip is nearby the adatom. Within the nonequilibrium Keldysh technique we analyze the interplay between the lateral displacement of the tip and the intra adatom Coulomb interaction on the spin-diode effect. As the tip moves away from the adatom the spin-diode effect vanishes and the currents become polarized for both V > 0 and V < 0. We also find an imbalance between the up and down spin populations in the adatom, which can be tuned by the tip position and the bias. Finally, due to the presence of the adsorbate on the surface, we observe spin-resolved Friedel oscillations in the current, which reflects the oscillations in the calculated local density of states (LDOS) of the subsystem surface + adatom.