979 resultados para Private Vehicle Transportation.
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Background: The transport of children in ground ambulances is a rarely studied topic worldwide. The ambulance vehicle is a unique and complex environment with particular challenges for the safe, correct and effective transportation of patients. Unlike the well developed and readily available guidelines on the safe transportation of a child in motor vehicles, there is a lack on consistent specifications for transporting children in ambulances. Nurses are called daily to transfer children to hospitals or other care centers, so safe transport practices should be a major concern. Purpose: to know which are the safety precautions and specific measures used in the transport of children in ground ambulances by nurses and firefighters and to identify what knowledge these professionals had about safe modes of children transportation in ground ambulances. Methods: In this context, an exploratory - descriptive study and quantitative analysis was conducted. A questionnaire was completed by 135 nurses and firefighters / ambulance crew based on 4 possible children transport scenarios proposed by the NHTSA (National Highway Traffic Safety Administration) and covered 5 different children´s age groups (new born children, 1 to 12 months; 1 to 3 years old; 4 to 7 years old and 8 to 12 years old). Results: The main results showed a variety of safety measures used by the professionals and a significant difference between their actual mode of transportation and the mode they consider to be the ideal considering security goals. In addition, findings showed that achieved scores related to what ambulance crews do in the considered scenarios reflect mostly satisfactory levels of transportation rather than optimum levels of safety, according to NHTSA recommendations. Variables as gender, educational qualifications, occupational group and local where professionals work seem to influence the transport options. Female professionals and nurses from pediatric units appear to do a safer transportation of children in ground ambulances than other professionals. Conclusion: Several professionals refereed unawareness of the safest transportation options for children in ambulances and did not to know the existence of specific recommendations for this type of transportation. The dispersion of the results suggests the need for investment in professional training and further regulation for this type of transportation.
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A vehicle holding method is proposed for mitigating the effect of service disruptions on coordinated intermodal freight operations. Existing studies are extended mainly by (1) modeling correlations among vehicle arrivals and (2) considering decision risks with a mean-standard deviation optimization model. It is shown that the expected value of the total cost in the proposed formulation is not affected by the correlations, while the variance can be miscomputed when arrival correlations are neglected. Some implications of delay propagation are also identified when optimizing vehicle holding decisions in real-time. General criteria are provided for determining the boundary of the affected region and length of the numerical search, based on the frequency of information updates. Theoretical analyses are supported by three numerical examples.
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This dissertation proposes statistical methods to formulate, estimate and apply complex transportation models. Two main problems are part of the analyses conducted and presented in this dissertation. The first method solves an econometric problem and is concerned with the joint estimation of models that contain both discrete and continuous decision variables. The use of ordered models along with a regression is proposed and their effectiveness is evaluated with respect to unordered models. Procedure to calculate and optimize the log-likelihood functions of both discrete-continuous approaches are derived, and difficulties associated with the estimation of unordered models explained. Numerical approximation methods based on the Genz algortithm are implemented in order to solve the multidimensional integral associated with the unordered modeling structure. The problems deriving from the lack of smoothness of the probit model around the maximum of the log-likelihood function, which makes the optimization and the calculation of standard deviations very difficult, are carefully analyzed. A methodology to perform out-of-sample validation in the context of a joint model is proposed. Comprehensive numerical experiments have been conducted on both simulated and real data. In particular, the discrete-continuous models are estimated and applied to vehicle ownership and use models on data extracted from the 2009 National Household Travel Survey. The second part of this work offers a comprehensive statistical analysis of free-flow speed distribution; the method is applied to data collected on a sample of roads in Italy. A linear mixed model that includes speed quantiles in its predictors is estimated. Results show that there is no road effect in the analysis of free-flow speeds, which is particularly important for model transferability. A very general framework to predict random effects with few observations and incomplete access to model covariates is formulated and applied to predict the distribution of free-flow speed quantiles. The speed distribution of most road sections is successfully predicted; jack-knife estimates are calculated and used to explain why some sections are poorly predicted. Eventually, this work contributes to the literature in transportation modeling by proposing econometric model formulations for discrete-continuous variables, more efficient methods for the calculation of multivariate normal probabilities, and random effects models for free-flow speed estimation that takes into account the survey design. All methods are rigorously validated on both real and simulated data.
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Strong evidence suggests that the climate is changing and that these changes are largely caused by human activities. A consensus exists among researchers that human activity is causing global warming and that actions to mitigate global warming need to be taken swiftly. The transportation sector, which relies heavily on fossil fuel burning and primarily oil, is one of the big contributors to air pollution problems at local, regional and global levels. It is the fastest growing source of greenhouse gas emissions and is estimated to be responsible for nearly a quarter of global energyrelated carbon dioxide emissions. Car sharing is a mobility solution encouraging its users to decrease private car usage in favour of communal transit and environmental goals. The idea of car sharing originates from the aspiration to decrease personal car ownership and to reduce vehicle distance travelled. This thesis seeks to complement the understanding of Finnish car sharing users and their usage through better categorization. Through better categorization and segmentation of Finnish car sharing users the thesis seeks to provide information for improved marketing insight. Research is done on the demographic and behavioural characteristics of Finnish car sharing users and they are compared with international findings about the characteristics of International car sharing users. The main research problem is Are Finnish car sharing users similar to international ones? A theoretical research framework on the determinants of individual car sharing usage is built based on international research about demographic and behaviouristic characteristics. After this a quantitative survey is performed to the customers of a Finnish car sharing organization. The data analysed in the thesis consist out of 532 answers received from the car sharing organizations customers. The data is analysed with descriptive and other exploratory methods, which create an understanding of Finnish car sharing users. At the end of the analysis the demographic and behavioural characteristics of Finnish car sharing users are compared with international ones. The research findings of the thesis indicate that the demographic and behavioural characteristics of Finnish car sharing usage largely follow those of their international counterparts. Thanks to the thesis results the car sharing organization is able to better target their customers through improved marketing insight.
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Part 21: Mobility and Logistics
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In the standard Vehicle Routing Problem (VRP), we route a fleet of vehicles to deliver the demands of all customers such that the total distance traveled by the fleet is minimized. In this dissertation, we study variants of the VRP that minimize the completion time, i.e., we minimize the distance of the longest route. We call it the min-max objective function. In applications such as disaster relief efforts and military operations, the objective is often to finish the delivery or the task as soon as possible, not to plan routes with the minimum total distance. Even in commercial package delivery nowadays, companies are investing in new technologies to speed up delivery instead of focusing merely on the min-sum objective. In this dissertation, we compare the min-max and the standard (min-sum) objective functions in a worst-case analysis to show that the optimal solution with respect to one objective function can be very poor with respect to the other. The results motivate the design of algorithms specifically for the min-max objective. We study variants of min-max VRPs including one problem from the literature (the min-max Multi-Depot VRP) and two new problems (the min-max Split Delivery Multi-Depot VRP with Minimum Service Requirement and the min-max Close-Enough VRP). We develop heuristics to solve these three problems. We compare the results produced by our heuristics to the best-known solutions in the literature and find that our algorithms are effective. In the case where benchmark instances are not available, we generate instances whose near-optimal solutions can be estimated based on geometry. We formulate the Vehicle Routing Problem with Drones and carry out a theoretical analysis to show the maximum benefit from using drones in addition to trucks to reduce delivery time. The speed-up ratio depends on the number of drones loaded onto one truck and the speed of the drone relative to the speed of the truck.
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This dissertation analyzes how individuals respond to the introduction of taxation aimed to reduce vehicle pollution, greenhouse gases and traffic. The first chapter analyzes a vehicle registration tax based on emissions of carbon dioxide (CO2), a major greenhouse gas, adopted in the UK in 2001 and subject to major changes in the following years. I identify the impact of the policy on new vehicle registrations and carbon emissions, compared to alternative measures. Results show that consumers respond to the tax by purchasing cleaner cars, but a carbon tax generating the same revenue would further reduce carbon emissions. The second chapter looks at a pollution charge (polluting vehicles pay to enter the city) and a congestion charge (all vehicles pay) adopted in 2008 and 2011 in Milan, Italy, and how they affected the concentration of nitrogen dioxides (NOx). I use data from pollution monitoring stations to measure the change between areas adopting the tax and other areas. Results show that in the first quarter of their introduction, both policies decreased NOx concentration in a range of -8% and -5%, but the effect declines over time, especially in the case of the pollution charge. The third chapter examines a trial conducted in 2005 in the Seattle, WA, area, in which vehicle trips by 276 volunteer households were recorded with a GPS device installed in their vehicles. Households received a monetary endowment which they used to pay a toll for each mile traveled: the toll varied with the time of the day, the day of the week and the type of road used. Using information on driving behavior, I show that in the first week a $0.10 toll per mile reduces the number of miles driven by around 7%, but the effect lasts only few weeks at most. The effect is mainly driven by a reduction in highway miles during trips from work to home, and it is strongly influenced by past driving behavior, income, the size of the initial endowment and the number of children in the household.
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Vehicle fuel consumption and emission are two important effectiveness measurements of sustainable transportation development. Pavement plays an essential role in goals of fuel economy improvement and greenhouse gas (GHG) emission reduction. The main objective of this dissertation study is to experimentally investigate the effect of pavement-vehicle interaction (PVI) on vehicle fuel consumption under highway driving conditions. The goal is to provide a better understanding on the role of pavement in the green transportation initiates. Four study phases are carried out. The first phase involves a preliminary field investigation to detect the fuel consumption differences between paired flexible-rigid pavement sections with repeat measurements. The second phase continues the field investigation by a more detailed and comprehensive experimental design and independently investigates the effect of pavement type on vehicle fuel consumption. The third study phase calibrates the HDM-IV fuel consumption model with data collected in the second field phase. The purpose is to understand how pavement deflection affects vehicle fuel consumption from a mechanistic approach. The last phase applies the calibrated HDM-IV model to Florida’s interstate network and estimates the total annual fuel consumption and CO2 emissions on different scenarios. The potential annual fuel savings and emission reductions are derived based on the estimation results. Statistical results from the two field studies both show fuel savings on rigid pavement compared to flexible pavement with the test conditions specified. The savings derived from the first phase are 2.50% for the passenger car at 112km/h, and 4.04% for 18-wheel tractor-trailer at 93km/h. The savings resulted from the second phase are 2.25% and 2.22% for passenger car at 93km/h and 112km/h, and 3.57% and 3.15% for the 6-wheel medium-duty truck at 89km/h and 105km/h. All savings are statistically significant at 95% Confidence Level (C.L.). From the calibrated HDM-IV model, one unit of pavement deflection (1mm) on flexible pavement can cause an excess fuel consumption by 0.234-0.311 L/100km for the passenger car and by 1.123-1.277 L/100km for the truck. The effect is more evident at lower highway speed than at higher highway speed. From the network level estimation, approximately 40 million gallons of fuel (combined gasoline and diesel) and 0.39 million tons of CO2 emission can be saved/reduced annually if all Florida’s interstate flexible pavement are converted to rigid pavement with the same roughness levels. Moreover, each 1-mile of flexible-rigid conversion can result in a reduction of 29 thousand gallons of fuel and 258 tons of CO2 emission yearly.
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The Equipment and Vehicle Revolving Fund report covers all equipment and vehicle purchases through the highway materials and equipment revolving fund during FY 2016.
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Background: The transport of children in ground ambulances is a rarely studied topic worldwide. The ambulance vehicle is a unique and complex environment with particular challenges for the safe, correct and effective transportation of patients. Unlike the well developed and readily available guidelines on the safe transportation of a child in motor vehicles, there is a lack on consistent specifications for transporting children in ambulances. Nurses are called daily to transfer children to hospitals or other care centers, so safe transport practices should be a major concern. Purpose: to know which are the safety precautions and specific measures used in the transport of children in ground ambulances by nurses and firefighters and to identify what knowledge these professionals had about safe modes of children transportation in ground ambulances. Methods: In this context, an exploratory - descriptive study and quantitative analysis was conducted. A questionnaire was completed by 135 nurses and firefighters / ambulance crew based on 4 possible children transport scenarios proposed by the NHTSA (National Highway Traffic Safety Administration) and covered 5 different children´s age groups (new born children, 1 to 12 months; 1 to 3 years old; 4 to 7 years old and 8 to 12 years old). Results: The main results showed a variety of safety measures used by the professionals and a significant difference between their actual mode of transportation and the mode they consider to be the ideal considering security goals. In addition, findings showed that achieved scores related to what ambulance crews do in the considered scenarios reflect mostly satisfactory levels of transportation rather than optimum levels of safety, according to NHTSA recommendations. Variables as gender, educational qualifications, occupational group and local where professionals work seem to influence the transport options. Female professionals and nurses from pediatric units appear to do a safer transportation of children in ground ambulances than other professionals. Conclusion: Several professionals refereed unawareness of the safest transportation options for children in ambulances and did not to know the existence of specific recommendations for this type of transportation. The dispersion of the results suggests the need for investment in professional training and further regulation for this type of transportation.
Resumo:
Summary The transport of children in ground ambulances is a rarely studied topic worldwide. The ambulance vehicle is a unique environment with particular challenges for the safe, correct and effective transportation of patients. Unlike the well developed and available guidelines on the transportation of children in motor vehicles, there is a lack on specifications for transporting children in ambulances. Nurses are called daily to transfer children to hospitals or other care centres, so safe transport practices should be a major concern. Methods An exploratory - descriptive study and quantitative analysis was conducted. The safety measures used by the professionals in the transportation of children in ambulances were analysed based on the NHTSA (National Highway Traffic Safety Administration) recommendations. A questionnaire was applied to 135 nurses and firefighters/crew of Portuguese ambulances using 4 possible transport situations and covering 5 paediatric age groups. Results There are a variety of safety measures used by professionals and a significant difference between actual mode of transportation and the mode they consider to be the ideal. In addition, findings showed that scores related to what ambulance crews do in these scenarios reflect most satisfactory levels of transportation rather than the optimum levels, according to NHTSA recommendations. Variables as gender, educational qualifications, occupational group and local where professionals work seem to influence the transport options. Female professionals and pediatric nurses do a safer transportation of children in ambulances than other professionals. Conclusion The results suggest the need for investment in professional training and further regulation for this type of transportation.