999 resultados para highway design
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International practice-led design research in landscape architecture has identified wetland sites as highly significant and potentially fragile environments in many countries. China has considerable wetland acreage that has been drained and transformed into farmland to address local poverty of farmers. An important gap in knowledge exists as to how to design Chinese public open spaces to reduce water contamination, flood severity and loss of farmland for local villagers as urban development expands. This project responded to the opportunity of introducing a new type of wetland design to Stage 3 of the Bailang River Redevelopment, Weifang City, Shandong Province. The work proposed a range of wetland design innovations for Chinese wetland environments to encourage on-site solutions to contamination and flooding problems.
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Highway construction works have significant bearings on all aspects of sustainability. With the increasing level of public awareness and government regulatory measures, the construction industry is experiencing a cultural shift to recognise, embrace and pursue sustainability. Stakeholders are now keen to identify sustainable alternatives and the financial implications of including them on a lifecycle basis. They need tools that can aid the evaluation of investment options. To date, however, there have not been many financial assessments on the sustainability aspects of highway projects. This is because the existing life-cycle costing analysis (LCCA) models tend to focus on economic issues alone and are not able to deal with sustainability factors. This paper provides insights into the current practice of life-cycle cost analysis, and the identification and quantification of sustainability-related cost components in highway projects through literature review, questionnaire surveys and semi-structured interviews. The results can serve as a platform for highway project stakeholders to develop practical tools to evaluate highway investment decisions and reach an optimum balance between financial viability and sustainability deliverables.
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Given the increasing cost of designing and building new highway pavements, reliability analysis has become vital to ensure that a given pavement performs as expected in the field. Recognizing the importance of failure analysis to safety, reliability, performance, and economy, back analysis has been employed in various engineering applications to evaluate the inherent uncertainties of the design and analysis. The probabilistic back analysis method formulated on Bayes' theorem and solved using the Markov chain Monte Carlo simulation method with a Metropolis-Hastings algorithm has proved to be highly efficient to address this issue. It is also quite flexible and is applicable to any type of prior information. In this paper, this method has been used to back-analyze the parameters that influence the pavement life and to consider the uncertainty of the mechanistic-empirical pavement design model. The load-induced pavement structural responses (e.g., stresses, strains, and deflections) used to predict the pavement life are estimated using the response surface methodology model developed based on the results of linear elastic analysis. The failure criteria adopted for the analysis were based on the factor of safety (FOS), and the study was carried out for different sample sizes and jumping distributions to estimate the most robust posterior statistics. From the posterior statistics of the case considered, it was observed that after approximately 150 million standard axle load repetitions, the mean values of the pavement properties decrease as expected, with a significant decrease in the values of the elastic moduli of the expected layers. An analysis of the posterior statistics indicated that the parameters that contribute significantly to the pavement failure were the moduli of the base and surface layer, which is consistent with the findings from other studies. After the back analysis, the base modulus parameters show a significant decrease of 15.8% and the surface layer modulus a decrease of 3.12% in the mean value. The usefulness of the back analysis methodology is further highlighted by estimating the design parameters for specified values of the factor of safety. The analysis revealed that for the pavement section considered, a reliability of 89% and 94% can be achieved by adopting FOS values of 1.5 and 2, respectively. The methodology proposed can therefore be effectively used to identify the parameters that are critical to pavement failure in the design of pavements for specified levels of reliability. DOI: 10.1061/(ASCE)TE.1943-5436.0000455. (C) 2013 American Society of Civil Engineers.
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The UK’s transport infrastructure is one of the most heavily used in the world. The performance of these networks is critically dependent on the performance of cutting and embankment slopes which make up £20B of the £60B asset value of major highway infrastructure alone. The rail network in particular is also one of the oldest in the world: many of these slopes are suffering high incidents of instability (increasing with time). This paper describes the development of a fundamental understanding of earthwork material and system behaviour, through the systematic integration of research across a range of spatial and temporal scales. Spatially these range from microscopic studies of soil fabric, through elemental materials behaviour to whole slope modelling and monitoring and scaling up to transport networks. Temporally, historical and current weather event sequences are being used to understand and model soil deterioration processes, and climate change scenarios to examine their potential effects on slope performance in futures up to and including the 2080s. The outputs of this research are being mapped onto the different spatial and temporal scales of infrastructure slope asset management to inform the design of new slopes through to changing the way in which investment is made into aging assets. The aim ultimately is to help create a more reliable, cost effective, safer and more resilient transport system.
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Internet today has become a vital part of day to day life, owing to the revolutionary changes it has brought about in various fields. Dependence on the Internet as an information highway and knowledge bank is exponentially increasing so that a going back is beyond imagination. Transfer of critical information is also being carried out through the Internet. This widespread use of the Internet coupled with the tremendous growth in e-commerce and m-commerce has created a vital need for infonnation security.Internet has also become an active field of crackers and intruders. The whole development in this area can become null and void if fool-proof security of the data is not ensured without a chance of being adulterated. It is, hence a challenge before the professional community to develop systems to ensure security of the data sent through the Internet.Stream ciphers, hash functions and message authentication codes play vital roles in providing security services like confidentiality, integrity and authentication of the data sent through the Internet. There are several ·such popular and dependable techniques, which have been in use widely, for quite a long time. This long term exposure makes them vulnerable to successful or near successful attempts for attacks. Hence it is the need of the hour to develop new algorithms with better security.Hence studies were conducted on various types of algorithms being used in this area. Focus was given to identify the properties imparting security at this stage. By making use of a perception derived from these studies, new algorithms were designed. Performances of these algorithms were then studied followed by necessary modifications to yield an improved system consisting of a new stream cipher algorithm MAJE4, a new hash code JERIM- 320 and a new message authentication code MACJER-320. Detailed analysis and comparison with the existing popular schemes were also carried out to establish the security levels.The Secure Socket Layer (SSL) I Transport Layer Security (TLS) protocol is one of the most widely used security protocols in Internet. The cryptographic algorithms RC4 and HMAC have been in use for achieving security services like confidentiality and authentication in the SSL I TLS. But recent attacks on RC4 and HMAC have raised questions about the reliability of these algorithms. Hence MAJE4 and MACJER-320 have been proposed as substitutes for them. Detailed studies on the performance of these new algorithms were carried out; it has been observed that they are dependable alternatives.
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This paper is an engineer's appreciation of environmental assessment with particular reference to highway development. While scheme-related Environmental Assessment for individual development may identify particular potential impacts, and may avoid or minimise some of the problems, in many cases it may be too late to take such actions. Ideally, Environmental Assessment should commence at the Strategic Level to cover policies, plan and programmes, and the scheme-related Environmental Assessments for individual projects should supplement those in the framework of Strategic Level. The utimate target is to assess the policy for their contribution to effecting sustainable development. Whole Life Environmental Impacts should be considered. These are the full impact consideration from planning, design and choice of materials, construction, operation and finally decommission. Most of the Environmental Assessments have not included the Whole Life Environmental Impacts. There is only limited monitoring in the operation stage after the construction of the scheme is complete, therefore, subsequent Environmental Assessments cannot benefit from the feedback of the scheme. No development should cost the Earth, hence Environmental Assessments have to be carried out thoroughly to serve as one of the instruments to meet the need of sustainable development.
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Private-Public Partnerships (P.P.P.) is a new contractual model institutionalized in 2004 that could be used to remedy to the infrastructure deficit in Brazil. In a context of a principal and agent relation, the public partner goal is to give incentives to the private partner in the contract so that their interests are aligned. This qualitative research presents the findings of an empirical study examining the performance of incentive PPP contracts in Brazil in the highway sector. The goal is to explain how the contracting parties can align their interests in an environment of asymmetric information. Literature identified the factors that can influence PPP design and efficient incentive contracts. The study assesses the contribution of these factors in the building of PPP contracts by focusing on the case of the first and only PPP signed in the highway sector in Brazil which is the MG-050. The first step is to describe the condition of the highway network and the level of compliance of the private partner with the contract PPP MG-050. The second step is to explain the performance of the private partner and conclude if the interests of both partners were aligned in contractual aspects. On the basis of these findings and the analysis of the contract, the study formulates suggestions to improve the draft of PPP contracts from the perspective of the incentive theory of contracts.
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This thesis aims to give a general view of pavement types all over the world, by showing the different characteristics of each one and its different life steps starting from construction, passing by maintenance and arriving until recycling phase. The flexible pavement took the main part of this work because it has been used in the last part of this thesis to design a project of a rural road. This project is located in the province of Bologna-Italy (‘Comune di Argelato’, 26 km in the north of Bologna), and has 5677, 81 m of length. A pavement design was made using the program BISAR 3.0 and a fatigue life study was made, also, in order to estimate the number of loads (in terms of heavy vehicles axle) to cause road’s failure . An alignment design was made for this project and a safety study was established in order to check if the available sight distance at curves respects the safety norms or not, by comparing it to the stopping sight distance. Different technical sheets are demonstrated and several cases are discussed in order to clarify the main design principles and underline the main hazardous cases to be avoided especially at intersection. This latter, its type’s choice depends on several factors in order to make the suitable design according to the environmental data. At this part of the road, the safety is a primordial point due to the high accident rate in this zone. For this reason, different safety aspects are discussed especially at roundabouts, signalized intersections, and also some other common intersection types. The design and the safety norms are taken with reference to AASHTO (American Association of State Highway and Transportation Officials), ACT (Transportation Association of Canada), and also according to Italian norms (Decreto Ministeriale delle Starde).
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A design can be defined as context-sensitive when it achieves effective technical and functional transportation solutions, while preserving and enhancing natural environments and minimizing impacts on local communities. Traffic noise is one of the most critical environmental impacts of transportation infrastructure and it affects both humans and ecosystems. Tire/pavement noise is caused by a set of interactions at the contact patch and it is the predominant source of road noise at the regular traffic speeds. Wearing course characteristics affect tire/pavement noise through various mechanisms. Furthermore, acoustic performance of road pavements varies over time and it is influenced by both aging and temperature. Three experimentations have been carried out to evaluate wearing course characteristics effects on tire/pavement noise. The first study involves the evaluation of skid resistance, surface texture and tire/pavement noise of an innovative application of multipurpose cold-laid microsurfacing. The second one involves the evaluation of the surface and acoustic characteristics of the different pavement sections of the test track of the Centre for Pavement and Transportation Technology (CPATT) at the University of Waterloo. In the third study, a set of highway sections have been selected in Southern Ontario with various types of pavements. Noise measurements were carried out by means of the Statistical Pass-by (SPB) method in the first case study, whereas in the second and in the third one, Close-proximity (CPX) and the On-Board Sound Intensity (OBSI) methods have been performed in parallel. Test results have contributed to understand the effects of pavement materials, temperature and aging on tire/pavement noise. Negligible correlation was found between surface texture and roughness with noise. As a general trend, aged and stiffer materials have shown to provide higher noise levels than newer and less stiff ones. Noise levels were also observed to be higher with temperature increase.
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The city of Madrid keeps not meeting the GHG and air pollutant limits set by the European legislation. A broad range of strategies have being taken into account to reduce both types of emissions; however traffic management meas ures are usually consigned to the sidelines. In 2004, Madrid City Council launched a plan to re-design its inner ring-road supported by a socioeconomic study that evaluated the environmental and operational benefits of the project. For safety reasons the planned speed limit for the tunnel section was finally reduced from 90km/h to 70km/h. Using a Macroscopic Traffic Model and the European Air Pollutant and Emissions Inventory Guidebook (EMEP/EEA), this paper examines the environmental and traffic performance consequences of this decision. Results support the thesis that reduced speed limits leads to GHG and air pollution reductions in the area affected by the measure without substantially altering traffic performance. The implementation of the new speed limit policy brings about a 15% and 16% reduction in both CO2 and NOx emissions respectively. Emissions’ reduction during off-peak hours is larger than during peak hours.
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Emergency management is one of the key aspects within the day-to-day operation procedures in a highway. Efficiency in the overall response in case of an incident is paramount in reducing the consequences of any incident. However, the approach of highway operators to the issue of incident management is still usually far from a systematic, standardized way. This paper attempts to address the issue and provide several hints on why this happens, and a proposal on how the situation could be overcome. An introduction to a performance based approach to a general system specification will be described, and then applied to a particular road emergency management task. A real testbed has been implemented to show the validity of the proposed approach. Ad-hoc sensors (one camera and one laser scanner) were efficiently deployed to acquire data, and advanced fusion techniques applied at the processing stage to reach the specific user requirements in terms of functionality, flexibility and accuracy.
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Highways can be effective barriers to animal migration. Where highways cross over streams, a passageway, typically a culvert, not designed for fish access can cut off an organism from miles of habitat. Traditional methods of culvert design, to convey floodwaters, reduced access to aquatic and riparian range. The Colorado Department of Transportation likely has numerous culverts that restrict aquatic passage. This paper provides guidance to CDOT for assessment of stream geomorphic conditions affecting culvert performance for fish passage, understanding aquatic organism habitat requirements, and incorporating ecological parameters into culvert designs that benefit fish and other organisms. A case study illustrates culvert problems in a difficult geomorphic setting including a fish passage assessment to evaluate stream stability for long-term culvert reliability.
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Arkansas State Highway and Transportation Department, Little Rock
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Federal Highway Administration, Office of Safety and Traffic Operations, Washington, D.C.
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National Highway Traffic Safety Administration, Washington, D.C.