Secondary collisions revisited: real-world crash data and relationship to crash test criteria

Objectives: Previous research conducted in the late 1980s suggested that vehicle impacts following an initial barrier collision increase severe occupant injury risk. Now over 25years old, the data are no longer representative of the currently installed barriers or the present US vehicle fleet. The purpose of this study is to provide a present-day assessment of secondary collisions and to determine if current full-scale barrier crash testing criteria provide an indication of secondary collision risk for real-world barrier crashes. Methods: To characterize secondary collisions, 1,363 (596,331 weighted) real-world barrier midsection impacts selected from 13years (1997-2009) of in-depth crash data available through the National Automotive Sampling System (NASS) / Crashworthiness Data System (CDS) were analyzed. Scene diagram and available scene photographs were used to determine roadside and barrier specific variables unavailable in NASS/CDS. Binary logistic regression models were developed for second event occurrence and resulting driver injury. To investigate current secondary collision crash test criteria, 24 full-scale crash test reports were obtained for common non-proprietary US barriers, and the risk of secondary collisions was determined using recommended evaluation criteria from National Cooperative Highway Research Program (NCHRP) Report 350. Results: Secondary collisions were found to occur in approximately two thirds of crashes where a barrier is the first object struck. Barrier lateral stiffness, post-impact vehicle trajectory, vehicle type, and pre-impact tracking conditions were found to be statistically significant contributors to secondary event occurrence. The presence of a second event was found to increase the likelihood of a serious driver injury by a factor of 7 compared to cases with no second event present. The NCHRP Report 350 exit angle criterion was found to underestimate the risk of secondary collisions in real-world barrier crashes. Conclusions: Consistent with previous research, collisions following a barrier impact are not an infrequent event and substantially increase driver injury risk. The results suggest that using exit-angle based crash test criteria alone to assess secondary collision risk is not sufficient to predict second collision occurrence for real-world barrier crashes.

Secondary Collisions Revisited: Real-World Crash Characteristics and Relationship to Crash Test Criteria

Previous research conducted in the late 1980’s suggested that vehicle impacts following an initial barrier collision increase severe occupant injury risk. Now over twenty-five years old, the data used in the previous research is no longer representative of the currently installed barriers or US vehicle fleet. The purpose of this study is to provide a present-day assessment of secondary collisions and to determine if full-scale barrier crash testing criteria provide an indication of secondary collision risk for real-world barrier crashes. The analysis included 1,383 (596,331 weighted) real-world barrier midsection impacts selected from thirteen years (1997-2009) of in-depth crash data available through the National Automotive Sampling System (NASS) / Crashworthiness Data System (CDS). For each suitable case, the scene diagram and available scene photographs were used to determine roadside and barrier specific variables not available in NASS/CDS. Binary logistic regression models were developed for second event occurrence and resulting driver injury. Barrier lateral stiffness, post-impact vehicle trajectory, vehicle type, and pre-impact tracking conditions were found to be statistically significant contributors toward secondary event occurrence. The presence of a second event was found to increase the likelihood of a serious driver injury by a factor of seven compared to cases with no second event present. Twenty-four full-scale crash test reports were obtained for common non-proprietary US barriers, and the risk of secondary collisions was determined using recommended evaluation criteria from NCHRP Report 350. It was found that the NCHRP Report 350 exit angle criterion alone was not sufficient to predict second collision occurrence for real-world barrier crashes.

Determining the role of environmental factors and disturbance in the distribution of reed canary grass within wetlands

Reed canary grass (Phalaris arundinacea L.) is an invasive species originally from Europe that has now expanded to a large range within the United States. Reed canary grass possesses a number of traits that allow it to thrive in a wide range of environmental factors, including high rates of sedimentation, bouts of flooding, and high levels of nutrient inputs. Therefore, the goals of our study were to determine if 1) certain types of wetland were more susceptible to Reed canary grass invasion, and 2) disturbances facilitated Reed canary grass invasion. This study was conducted within the Keweenaw Bay Indian Community reservation in the Upper Peninsula of Michigan, in Baraga County. We selected 28 wetlands for analysis. At each wetland, we identified and sampled distinct vegetative communities and their corresponding environmental attributes, which included water table depth, pH, conductivity, calcium and magnesium concentrations, and percent organic matter. Disturbances at each site were catalogued and their severity estimated with the aid of aerial photos. A GIS dataset containing information about the location of Reed canary grass within the study wetlands, the surrounding roads and the level of roadside Reed canary grass invasion was also developed. In all, 287 plant species were identified and classified into 16 communities, which were then further grouped into three broad groupings of wetlands: nonforested graminoid, Sphagnum peatlands, and forested wetlands. The two most common disturbances identified were roads and off-road recreation trails, both occurring at 23 of the 28 sites. Logging activity surrounding the wetlands was the next most common disturbance and was found at 18 of the sites. Occurrence of Reed canary grass was most common in the non-forested graminoid communities. Reed canary grass was very infrequent in forested wetlands, and almost never occurred in the Sphagnum peatlands. Disturbance intensity was the most significant environmental factor in explaining Reed canary grass occurrence within wetlands. Statistically significant relationships were identified at distances of 1000 m, 500 m, and 250 m from studied wetlands, between the level of road development and the severity of Reed canary grass invasion along roadsides. Further analysis revealed a significant relationship between roadside Reed canary grass populations and the level of road development (e.g. paved, graded, and ungraded).

INTEGRATED MANAGEMENT OF THE INVASIVE SPECIES CIRSIUM ARVENSE, CANADA THISTLE, AND PHRAGMITES AUSTRALIS, COMMON REED: USING ECOLOGICALLY BASED CONTROL MEASURES AT EACH STAGE OF THE INVASION PROCESS

Invasive plant species threaten natural areas by reducing biodiversity and altering ecosystem functions. They also impact agriculture by reducing crop and livestock productivity. Millions of dollars are spent on invasive species control each year, and traditionally, herbicides are used to manage invasive species. Herbicides have human and environmental health risks associated with them; therefore, it is essential that land managers and stakeholders attempt to reduce these risks by utilizing the principles of integrated weed management. Integrated weed management is a practice that incorporates a variety of measures and focuses on the ecology of the invasive plant to manage it. Roadways are high risk areas that have high incidence of invasive species. Roadways act as conduits for invasive species spread and are ideal harborages for population growth; therefore, roadways should be a primary target for invasive species control. There are four stages in the invasion process which an invasive species must overcome: transport, establishment, spread, and impact. The aim of this dissertation was to focus on these four stages and examine the mechanisms underlying the progression from one stage to the next, while also developing integrated weed management strategies. The target species were Phragmites australis, common reed, and Cisrium arvense, Canada thistle. The transport and establishment risks of P. australis can be reduced by removing rhizome fragments from soil when roadside maintenance is performed. The establishment and spread of C. arvense can be reduced by planting particular resistant species, e.g. Heterotheca villosa, especially those that can reduce light transmittance to the soil. Finally, the spread and impact of C. arvense can be mitigated on roadsides through the use of the herbicide aminopyralid. The risks associated with herbicide drift produced by application equipment can be reduced by using the Wet-Blade herbicide application system.

Effects of Chemical Deicers on Amphibian Communites

Roads and highways present a unique challenge to wildlife as they exhibit substantial impacts on the surrounding ecosystem through the interruption of a number of ecological processes. With new roads added to the national highway system every year, an understanding of these impacts is required for effective mitigation of potential environmental impacts. A major contributor to these negative effects is the deposition of chemicals used in winter deicing activities to nearby surface waters. These chemicals often vary in composition and may affect freshwater species differently. The negative impacts of widespread deposition of sodium chloride (NaCl) have prompted a search for an `environmentally friendly' alternative. However, little research has investigated the potential environmental effects of widespread use of these alternatives. Herein, I detail the results of laboratory tests and field surveys designed to determine the impacts of road salt (NaCl) and other chemical deicers on amphibian communities in Michigan's Upper Peninsula. Using larval amphibians I demonstrate the lethal impacts of a suite of chemical deicers on this sensitive, freshwater species. Larval wood frogs (Lithobates sylvatica) were tolerant of short-term (96 hours) exposure to urea (CH4N2O), sodium chloride (NaCl), and magnesium chloride (MgCl2). However, these larvae were very sensitive to acetate products (C8H12CaMgO8, CH3COOK) and calcium chloride (CaCl2). These differences in tolerance suggest that certain deicers may be more harmful to amphibians than others. Secondly, I expanded this analysis to include an experiment designed to determine the sublethal effects of chronic exposure to environmentally realistic concentrations of NaCl on two unique amphibian species, L. sylvatica and green frogs (L. clamitans). L. sylvatica tend to breed in small, ephemeral wetlands and metamorphose within a single season. However, L. clamitans breed primarily in more permanent wetlands and often remain as tadpoles for one year or more. These species employ different life history strategies in this region which may influence their response to chronic NaCl exposure. Both species demonstrated potentially harmful effects on individual fitness. L. sylvatica larvae had a high incidence of edema suggesting the NaCl exposure was a significant physiologic stressor to these larvae. L. clamitans larvae reduced tail length during their exposure which may affect adult fitness of these individuals. In order to determine the risk local amphibians face when using these roadside pools, I conducted a survey of the spatial distribution of chloride in the three northernmost counties of Michigan. This area receives a relatively low amount of NaCl which is confined to state and federal highways. The chloride concentrations in this region were much lower than those in urban systems; however, amphibians breeding in the local area may encounter harmful chloride levels arising from temporal variations in hydroperiods. Spatial variation of chloride levels suggests the road-effect zone for amphibians may be as large as 1000 m from a salt-treated highway. Lastly, I performed an analysis of the use of specific conductance to predict chloride concentrations in natural surface water bodies. A number of studies have used this regression to predict chloride concentrations from measurements of specific conductance. This method is often chosen in the place of ion chromatography due to budget and time constraints. However, using a regression method to characterize this relationship does not result in accurate chloride ion concentration estimates.

Isotope fractionation of selenium by biomethylation in microcosm incubations of soil

The natural abundance of stable Se isotopes in methylselenides reflects sources and formation conditions of methylselenides. We tested the effects of (i) different inorganic Se species spiked to soils and (ii) different soil samples on the extent of fungal biomethylation of Se and the Se isotope ratios (δ82/76Se) in methylselenides. Furthermore, we assessed the decrease of dissolved, bioavailable Se during three days of equilibration of the soils with Se-enriched solutions. We conducted closed microcosm experiments containing soil spiked with Se(IV) or Se(VI), a growth medium, and the fungus species Alternaria alternata for 11 d. The concentrations and isotope ratios of Se were determined in all components of the microcosm with multicollector ICP-MS. The equilibration of the spiked Se(IV) and Se(VI) for 3 d resulted in a decrease of dissolved, bioavailable Se concentrations by 32 to 44% and 8 to 14%, respectively. Very little isotope fractionation occurred during this phase, and it can be attributed to mixing of the added Se with the pre-existing Se in the soils and minor Se(IV) reduction in one experiment. In two of the incubated soils – moderately acidic roadside and garden soils – between 9.1 and 30% of the supplied Se(IV) and 1.7% of the supplied Se(VI) were methylated while in a strongly acidic forest soil no Se methylation occurred. The methylselenides derived from Se(IV) were strongly depleted in 82Se (δ82/76Se = − 3.3 to − 4.5‰) compared with the soil (0.16–0.45‰) and the added Se(IV) (0.20‰). The methylselenide yield of the incubations with Se(VI) was too small for isotope measurements. Our results demonstrate that Se source species and soil properties influence the extent of Se biomethylation and that the produced methylselenides contain isotopically light Se.

A standard operation procedure and a pilot water testing for herbicides in northwest Harris County, Texas

Herbicides are used to control the growth of weeds along highways, power lines, and many other urban locations. Exposure to herbicides has been linked to adverse health outcomes. This study was initiated to pretest for the presence of herbicides in multiple water sources near intersections in a corridor in the Northwest Harris County (specifically in the Highway 6/FM 1960, North Freeway 45, US 290 and S 99 corridor). Roadside water and tap water samples were collected and analyzed for herbicides using the established Environmental Protection Agency (EPA) Method 515.4: "Determination of Chlorinated Acids in Drinking Water by Liquid-Liquid Micro-extraction, Derivatization, and Fast Gas Chromatography with Electron Capture Detection." A standard operating procedure (adapted from the US EPA Method 515.4) was developed for subsequent, larger studies of environmental fate of herbicides and non-occupational exposure risks. Preliminary testing of 16 water samples was performed to pretest the existence of trace herbicides; all concentrations that were greater than the minimum reporting limits of each analyte are reported with a 99 percent confidence. This study failed to find concentrations above the limits of detection of the method in any of the samples collected on June 15, 2008. However, this does not indicate that the waters around the NW Harris County are free of herbicides and metabolites. A larger and repeated sampling in the region would be necessary to make that claim. ^

Economic development capitalizing on brand agriculture : turning development strategy on its head

This paper explores the possibilities of two unique Japanese concepts - the One Village One Product Movement (OVOP) and Michino Eki (or Roadside Stations) - as potential tools for bridging the gap between cities and rural areas through community-driven development. From the viewpoint of spatial economics and endogenous growth theory, this paper considers both OVOP and Michino Eki as rural development strategies of a broader nature based on "brand agriculture." Here, brand agriculture represents a general strategy for community-based rural development that identifies, cultivates and fully utilizes local resources for the development of products or services unique to a certain "village." Selected examples of OVOP and Michino Eki from Japan and developing countries are introduced.

Levels, sources and seasonality of coarse particles (PM10-PM2.5) in three European capitals e implications for particulate pollution control

Coarse particles of aerodynamic diameter between 2.5 and 10 mm (PMc) are produced by a range of natural (windblown dust and sea sprays) and anthropogenic processes (non-exhaust vehicle emissions, industrial, agriculture, construction and quarrying activities). Although current ambient air quality regulations focus on PM2.5 and PM10, coarse particles are of interest from a public health point of view as they have been associated with certain mortality and morbidity outcomes. In this paper, an analysis of coarse particle levels in three European capitals (London, Madrid and Athens) is presented and discussed. For all three cities we analysed data from both traffic and urban background monitoring sites. The results showed that the levels of coarse particles present significant seasonal, weekly and daily variability. Their wind driven and non-wind driven resuspension as well as their roadside increment due to traffic were estimated. Both the local meteorological conditions and the air mass history indicating long-range atmospheric transport of particles of natural origin are significant parameters that influence the levels of coarse particles in the three cities especially during episodic events.

Study of PM10 and PM2.5 levels in three European cities: Analysis of intra and inter urban variations

In the present paper, 1-year PM10 and PM 2.5 data from roadside and urban background monitoring stations in Athens (Greece), Madrid (Spain) and London (UK) are analysed in relation to other air pollutants (NO,NO2,NOx,CO,O3 and SO2)and several meteorological parameters (wind velocity, temperature, relative humidity, precipitation, solar radiation and atmospheric pressure), in order to investigate the sources and factors affecting particulate pollution in large European cities. Principal component and regression analyses are therefore used to quantify the contribution of both combustion and non-combustion sources to the PM10 and PM 2.5 levels observed. The analysis reveals that the EU legislated PM 10 and PM2.5 limit values are frequently breached, forming a potential public health hazard in the areas studied. The seasonal variability patterns of particulates varies among cities and sites, with Athens and Madrid presenting higher PM10 concentrations during the warm period and suggesting the larger relative contribution of secondary and natural particles during hot and dry days. It is estimated that the contribution of non-combustion sources varies substantially among cities, sites and seasons and ranges between 38-67% and 40-62% in London, 26-50% and 20-62% in Athens, and 31-58% and 33-68% in Madrid, for both PM10 and PM 2.5. Higher contributions from non-combustion sources are found at urban background sites in all three cities, whereas in the traffic sites the seasonal differences are smaller. In addition, the non-combustion fraction of both particle metrics is higher during the warm season at all sites. On the whole, the analysis provides evidence of the substantial impact of non-combustion sources on local air quality in all three cities. While vehicular exhaust emissions carry a large part of the risk posed on human health by particle exposure, it is most likely that mitigation measures designed for their reduction will have a major effect only at traffic sites and additional measures will be necessary for the control of background levels. However, efforts in mitigation strategies should always focus on optimal health effects.

Sobre el comportamiento de micropilotes trabajando a flexión y/o cortante en estructuras de tierra

El empleo de los micropilotes en la ingeniería civil ha revolucionado las técnicas de estabilización de terraplenes a media ladera, ya que aunque los pilotes pueden ser la opción más económica, el uso de micropilotes permite llegar a sitios inaccesibles con menor coste de movimientos de tierras, realización de plataformas de trabajo de dimensiones reducidas, maquinaria necesaria es mucho más pequeña, liviana y versátil en su uso, incluyendo la posibilidad de situar la fabricación de morteros o lechadas a distancias de varias decenas de metros del elemento a ejecutar. Sin embargo, realizando una revisión de la documentación técnica que se tiene en el ámbito ingenieril, se comprobó que los sistemas de diseño de algunos casos (micropilotes en terraplenes a media ladera, micropilotes en pantallas verticales, micropilotes como “paraguas” en túneles, etc.) eran bastante deficientes o poco desarrollados. Premisa que permite concluir que el constructor ha ido por delante (como suele ocurrir en ingeniería geotécnica) del cálculo o de su análisis teórico. Del mismo modo se determinó que en su mayoría los micropilotes se utilizan en labores de recalce o como nueva solución de cimentación en condiciones de difícil acceso, casos en los que el diseño de los micropilotes viene definido por cargas axiales, de compresión o de tracción, consideraciones que se contemplan en reglamentaciones como la “Guía para el proyecto y la ejecución de micropilotes en obras de carretera” del Ministerio de Fomento. En los micropilotes utilizados para estabilizar terraplenes a media ladera y micropilotes actuando como muros pantalla, en los que éstos trabajan a esfuerzo cortante y flexión, no se dispone de sistemas de análisis fiables o no se introduce adecuadamente el problema de interacción terreno-micropilote. Además en muchos casos, los parámetros geotécnicos que se utilizan no tienen una base técnico-teórica adecuada por lo que los diseños pueden quedar excesivamente del lado de la seguridad, en la mayoría de los casos, o todo lo contrario. Uno de los objetivos principales de esta investigación es estudiar el comportamiento de los micropilotes que están sometidos a esfuerzos de flexión y cortante, además de otros objetivos de gran importancia que se describen en el apartado correspondiente de esta tesis. Cabe indicar que en este estudio no se ha incluido el caso de micropilotes quasi-horizontales trabajando a flexion (como los “paraguas” en túneles), por considerarse que estos tienen un comportamiento y un cálculo diferente, que está fuera del alcance de esta investigación. Se ha profundizado en el estudio del empleo de micropilotes en taludes, presentando casos reales de obras ejecutadas, datos estadísticos, problemas de diseño y ejecución, métodos de cálculo simplificados y modelación teórica en cada caso, efectuada mediante el empleo de elementos finitos con el Código Plaxis 2D. Para llevar a cabo los objetivos que se buscan con esta investigación, se ha iniciado con el desarrollo del “Estado del Arte” que ha permitido establecer tipología, aplicaciones, características y cálculo de los micropilotes que se emplean habitualmente. Seguidamente y a efectos de estudiar el problema dentro de un marco geotécnico real, se ha seleccionado una zona española de actuación, siendo ésta Andalucía, en la que se ha utilizado de manera muy importante la técnica de micropilotes sobre todo en problemas de estabilidad de terraplenes a media ladera. A partir de ahí, se ha realizado un estudio de las propiedades geotécnicas de los materiales (principalmente suelos y rocas muy blandas) que están presentes en esta zona geográfica, estudio que ha sido principalmente bibliográfico o a partir de la experiencia en la zona del Director de esta tesis. Del análisis realizado se han establecido ordenes de magnitud de los parámetros geotécnicos, principalmente la cohesión y el ángulo de rozamiento interno (además del módulo de deformación aparente o de un módulo de reacción lateral equivalente) para los diversos terrenos andaluces. Con el objeto de conocer el efecto de la ejecución de un micropilote en el terreno (volumen medio real del micropilote, una vez ejecutado; efecto de la presión aplicada en las propiedades del suelo circundante, etc.) se ha realizado una encuesta entre diversas empresas españolas especializadas en la técnica de los micropilotes, a efectos de controlar los volúmenes de inyección y las presiones aplicadas, en función de la deformabilidad del terreno circundante a dichos micropilotes, con lo que se ha logrado definir una rigidez a flexión equivalente de los mismos y la definición y características de una corona de terreno “mejorado” lograda mediante la introducción de la lechada y el efecto de la presión alrededor del micropilote. Con las premisas anteriores y a partir de los parámetros geotécnicos determinados para los terrenos andaluces, se ha procedido a estudiar la estabilidad de terraplenes apoyados sobre taludes a media ladera, mediante el uso de elementos finitos con el Código Plaxis 2D. En el capítulo 5. “Simulación del comportamiento de micropilotes estabilizando terraplenes”, se han desarrollado diversas simulaciones. Para empezar se simplificó el problema simulando casos similares a algunos reales en los que se conocía que los terraplenes habían llegado hasta su situación límite (de los que se disponía información de movimientos medidos con inclinómetros), a partir de ahí se inició la simulación de la inestabilidad para establecer el valor de los parámetros de resistencia al corte del terreno (mediante un análisis retrospectivo – back-análisis) comprobando a su vez que estos valores eran similares a los deducidos del estudio bibliográfico. Seguidamente se han introducido los micropilotes en el borde de la carretera y se ha analizado el comportamiento de éstos y del talud del terraplén (una vez construidos los micropilotes), con el objeto de establecer las bases para su diseño. De este modo y adoptando los distintos parámetros geotécnicos establecidos para los terrenos andaluces, se simularon tres casos reales (en Granada, Málaga y Ceuta), comparando los resultados de dichas simulaciones numéricas con los resultados de medidas reales de campo (desplazamientos del terreno, medidos con inclinómetros), obteniéndose una reproducción bastante acorde a los movimientos registrados. Con las primeras simulaciones se concluye que al instalar los micropilotes la zona más insegura de la ladera es la de aguas abajo. La superficie de rotura ya no afecta a la calzada que protegen los micropilotes. De ahí que se deduzca que esta solución sea válida y se haya aplicado masivamente en Andalucía. En esas condiciones, podría decirse que no se está simulando adecuadamente el trabajo de flexión de los micropilotes (en la superficie de rotura, ya que no les corta), aunque se utilicen elementos viga. Por esta razón se ha realizado otra simulación, basada en las siguientes hipótesis: − Se desprecia totalmente la masa potencialmente deslizante, es decir, la que está por delante de la fila exterior de micros. − La estratigrafía del terreno es similar a la considerada en las primeras simulaciones. − La barrera de micropilotes está constituida por dos elementos inclinados (uno hacia dentro del terraplén y otro hacia fuera), con inclinación 1(H):3(V). − Se puede introducir la rigidez del encepado. − Los micros están separados 0,556 m ó 1,00 m dentro de la misma alineación. − El empotramiento de los micropilotes en el sustrato resistente puede ser entre 1,5 y 7,0 m. Al “anular” el terreno que está por delante de los micropilotes, a lo largo del talud, estos elementos empiezan claramente a trabajar, pudiendo deducirse los esfuerzos de cortante y de flexión que puedan actuar sobre ellos (cota superior pero prácticamente muy cerca de la solución real). En esta nueva modelación se ha considerado tanto la rigidez equivalente (coeficiente ϴ) como la corona de terreno tratado concéntrico al micropilote. De acuerdo a esto último, y gracias a la comparación de estas modelaciones con valores reales de movimientos en laderas instrumentadas con problemas de estabilidad, se ha verificado que existe una similitud bastante importante entre los valores teóricos obtenidos y los medidos en campo, en relación al comportamiento de los micropilotes ejecutados en terraplenes a media ladera. Finalmente para completar el análisis de los micropilotes trabajando a flexión, se ha estudiado el caso de micropilotes dispuestos verticalmente, trabajando como pantallas discontinuas provistas de anclajes, aplicado a un caso real en la ciudad de Granada, en la obra “Hospital de Nuestra Señora de la Salud”. Para su análisis se utilizó el código numérico CYPE, basado en que la reacción del terreno se simula con muelles de rigidez Kh o “módulo de balasto” horizontal, introduciendo en la modelación como variables: a) Las diferentes medidas obtenidas en campo; b) El espesor de terreno cuaternario, que por lo que se pudo determinar, era variable, c) La rigidez y tensión inicial de los anclajes. d) La rigidez del terreno a través de valores relativos de Kh, recopilados en el estudio de los suelos de Andalucía, concretamente en la zona de Granada. Dicha pantalla se instrumentó con 4 inclinómetros (introducidos en los tubos de armadura de cuatro micropilotes), a efectos de controlar los desplazamientos horizontales del muro de contención durante las excavaciones pertinentes, a efectos de comprobar la seguridad del conjunto. A partir del modelo de cálculo desarrollado, se ha comprobado que el valor de Kh pierde importancia debido al gran número de niveles de anclajes, en lo concerniente a las deformaciones horizontales de la pantalla. Por otro lado, los momentos flectores son bastante sensibles a la distancia entre anclajes, al valor de la tensión inicial de los mismos y al valor de Kh. Dicho modelo también ha permitido reproducir de manera fiable los valores de desplazamientos medidos en campo y deducir los parámetros de deformabilidad del terreno, Kh, con valores del orden de la mitad de los medidos en el Metro Ligero de Granada, pero visiblemente superiores a los deducibles de ábacos que permiten obtener Kh para suelos granulares con poca cohesión (gravas y cuaternario superior de Sevilla) como es el caso del ábaco de Arozamena, debido, a nuestro juicio, a la cementación de los materiales presentes en Granada. En definitiva, de las anteriores deducciones se podría pensar en la optimización del diseño de los micropilotes en las obras que se prevean ejecutar en Granada, con similares características al caso de la pantalla vertical arriostrada mediante varios niveles de anclajes y en las que los materiales de emplazamiento tengan un comportamiento geotécnico similar a los estudiados, con el consiguiente ahorro económico. Con todo ello, se considera que se ha hecho una importante aportación para el diseño de futuras obras de micropilotes, trabajando a flexión y cortante, en obras de estabilización de laderas o de excavaciones. Using micropiles in civil engineering has transformed the techniques of stabilization of embankments on the natural or artificial slopes, because although the piles may be the cheapest option, the use of micropiles can reach inaccessible places with lower cost of earthworks, carrying out small work platforms. Machinery used is smaller, lightweight and versatile, including the possibility of manufacturing mortars or cement grouts over distances of several tens of meters of the element to build. However, making a review of the technical documentation available in the engineering field, it was found that systems designed in some cases (micropiles in embankments on the natural slopes, micropiles in vertical cut-off walls, micropiles like "umbrella" in tunnels, etc.) were quite poor or underdeveloped. Premise that concludes the builder has gone ahead (as usually happen in geotechnical engineering) of calculation or theoretical analysis. In the same way it was determined that most of the micropiles are used in underpinning works or as a new foundation solution in conditions of difficult access, in which case the design of micropiles is defined by axial, compressive or tensile loads, considered in regulations as the " Handbook for the design and execution of micropiles in road construction" of the Ministry of Development. The micropiles used to stabilize embankments on the slopes and micropiles act as retaining walls, where they work under shear stress and bending moment, there are not neither reliable systems analysis nor the problem of soil-micropile interaction are properly introduced. Moreover, in many cases, the geotechnical parameters used do not have a proper technical and theoretical basis for what designs may be excessively safe, or the opposite, in most cases. One of the main objectives of this research is to study the behavior of micro piles which are subjected to bending moment and shear stress, as well as other important objectives described in the pertinent section of this thesis. It should be noted that this study has not included the case of quasi-horizontal micropiles working bending moment (as the "umbrella" in tunnels), because it is considered they have a different behavior and calculation, which is outside the scope of this research. It has gone in depth in the study of using micropiles on slopes, presenting real cases of works made, statistics, problems of design and implementation, simplified calculation methods and theoretical modeling in each case, carried out by using FEM (Finite Element Method) Code Plaxis 2D. To accomplish the objectives of this research, It has been started with the development of the "state of the art" which stipulate types, applications, characteristics and calculation of micropiles that are commonly used. In order to study the problem in a real geotechnical field, it has been selected a Spanish zone of action, this being Andalusia, in which it has been used in a very important way, the technique of micropiles especially in embankments stability on natural slopes. From there, it has made a study of the geotechnical properties of the materials (mainly very soft soils and rocks) that are found in this geographical area, which has been mainly a bibliographic study or from the experience in the area of the Director of this thesis. It has been set orders of magnitude of the geotechnical parameters from analyzing made, especially the cohesion and angle of internal friction (also apparent deformation module or a side reaction module equivalent) for various typical Andalusian ground. In order to determine the effect of the implementation of a micropile on the ground (real average volume of micropile once carried out, effect of the pressure applied on the properties of the surrounding soil, etc.) it has conducted a survey among various skilled companies in the technique of micropiles, in order to control injection volumes and pressures applied, depending on the deformability of surrounding terrain such micropiles, whereby it has been possible to define a bending stiffness and the definition and characteristics of a crown land "improved" achieved by introducing the slurry and the effect of the pressure around the micropile. With the previous premises and from the geotechnical parameters determined for the Andalusian terrain, we proceeded to study the stability of embankments resting on batters on the slope, using FEM Code Plaxis 2D. In the fifth chapter "Simulation of the behavior of micropiles stabilizing embankments", there were several different numerical simulations. To begin the problem was simplified simulating similar to some real in which it was known that the embankments had reached their limit situation (for which information of movements measured with inclinometers were available), from there the simulation of instability is initiated to set the value of the shear strength parameters of the ground (by a retrospective analysis or back-analysis) checking these values were similar to those deduced from the bibliographical study Then micropiles have been introduced along the roadside and its behavior was analyzed as well as the slope of embankment (once micropiles were built ), in order to establish the basis for its design. In this way and taking the different geotechnical parameters for the Andalusian terrain, three real cases (in Granada, Malaga and Ceuta) were simulated by comparing the results of these numerical simulations with the results of real field measurements (ground displacements measured with inclinometers), getting quite consistent information according to registered movements. After the first simulations it has been concluded that after installing the micropiles the most insecure area of the natural slope is the downstream. The failure surface no longer affects the road that protects micropiles. Hence it is inferred that this solution is acceptable and it has been massively applied in Andalusia. Under these conditions, one could say that it is not working properly simulating the bending moment of micropiles (on the failure surface, and that does not cut them), although beam elements are used. Therefore another simulation was performed based on the following hypotheses: − The potentially sliding mass is totally neglected, that is, which is ahead of the outer row of micropiles. − Stratigraphy field is similar to the one considered in the first simulations. − Micropiles barrier is constituted by two inclined elements (one inward and one fill out) with inclination 1 (H): 3 (V). − You can enter the stiffness of the pile cap. − The microlies lines are separated 0.556 m or 1.00 m in the same alignment. − The embedding of the micropiles in the tough substrate can be between 1.5 and 7.0 m. To "annul" the ground that is in front of the micro piles, along the slope, these elements clearly start working, efforts can be inferred shear stress and bending moment which may affect them (upper bound but pretty close to the real) solution. In this new modeling it has been considered both equivalent stiffness coefficient (θ) as the treated soil crown concentric to the micropile. According to the latter, and by comparing these values with real modeling movements on field slopes instrumented with stability problems, it was verified that there is quite a significant similarity between the obtained theoretical values and the measured field in relation to the behavior of micropiles executed in embankments along the natural slope. Finally to complete the analysis of micropiles working in bending conditions, we have studied the case of micropiles arranged vertically, working as discontinued cut-off walls including anchors, applied to a real case in the city of Granada, in the play "Hospital of Our Lady of the Health ". CYPE numeric code, based on the reaction of the ground is simulated spring stiffness Kh or "subgrade" horizontal, introduced in modeling was used as variables for analysis: a) The different measurements obtained in field; b) The thickness of quaternary ground, so that could be determined, was variable, c) The stiffness and the prestress of the anchors. d) The stiffness of the ground through relative values of Kh, collected in the study of soils in Andalusia, particularly in the area of Granada. (previously study of the Andalusia soils) This cut-off wall was implemented with 4 inclinometers (introduced in armor tubes four micropiles) in order to control the horizontal displacements of the retaining wall during the relevant excavations, in order to ensure the safety of the whole. From the developed model calculation, it was found that the value of Kh becomes less important because a large number of anchors levels, with regard to the horizontal deformation of the cut-off wall. On the other hand, the bending moments are quite sensitive to the distance between anchors, the initial voltage value thereof and the value of Kh. This model has also been reproduced reliably displacement values measured in the field and deduce parameters terrain deformability, Kh, with values around half the measured Light Rail in Granada, but visibly higher than deductible of abacuses which can obtain Kh for granular soils with low cohesion (upper Quaternary gravels and Sevilla) such as Abacus Arozamena, because, in our view, to cementing materials in Granada. In short, previous deductions you might think on optimizing the design of micropiles in the works that are expected to perform in Granada, with similar characteristics to the case of the vertical cut-off wall braced through several levels of anchors and in which materials location have a geotechnical behavior similar to those studied, with the consequent economic savings. With all this, it is considered that a significant contribution have been made for the design of future works of micropiles, bending moment and shear stress working in slope stabilization works or excavations.

Poluição sonora urbana: a influência de modificações em escapamentos de motocicletas na emissão de ruído

A poluição sonora urbana, em especial a gerada por motocicletas com escapamentos modificados, afeta indistintamente a saúde de toda população de diversas maneiras e tende a aumentar, ao contrário da emissão de gases, que vem se reduzindo ao longo dos anos. Com o objetivo de conter o ruído gerado pelo tráfego urbano, vários países desenvolvem procedimentos, leis e ações mitigatórias como barreiras acústicas e asfaltos fonoabsorventes, porém há grande quantidade de motocicletas, veículo tipicamente de alto potencial de incômodo e ruidoso, que circulam com sistemas de escapamento adulterados e emitem ainda mais excesso de ruído. A inspeção veicular é ferramenta importante no controle de emissões de gases poluentes de veículos em uso, mas falha em restringir aqueles que ultrapassam os limites legais de ruído e, somado a isto, há o agravante de o condutor submeter-se a poluição sonora que ele mesmo produz. A fiscalização de rua surge como alternativa de controle ambiental, mas algumas vezes é contestada por ser subjetiva ou por faltar uma metodologia simples, confiável e eficaz. Buscou-se então compreender a relação entre o aumento do nível sonoro da motocicleta com escapamento modificado ao circular no trânsito e a emissão sonora medida na condição de inspeção, o chamado ruído parado, para trazer subsídios à formação de métodos mais eficazes de fiscalização e controle. Para isto foram avaliadas motocicletas quanto à emissão de ruído em circulação e ruído parado e os resultados obtidos apontam que os escapamentos modificados possuem nível sonoro muito mais elevado que os originais, com forte correspondência entre os dois métodos de medição. Esta poluição sonora atinge de modo particularmente intenso os profissionais, motoboys, que modificam suas motocicletas, pois eles se submetem a todos os fatores que favorecem a perda auditiva por excesso de ruído. Outras questões surgiram em paralelo ao tema principal e foram brevemente avaliadas para se compor o quadro geral, como o nível sonoro de escapamentos não originais avaliados segundo os procedimentos de homologação, a contribuição que a motocicleta traz ao ruído urbano e que resultados estes trazem quanto ao torque e potência da motocicleta. Estes estudos indicaram que a motocicleta modificada contribui fortemente para a poluição sonora urbana, afetando principalmente o condutor e sem trazer ganhos efetivos em termos de potência e dirigibilidade.

SOA-Based Model for Value-Added ITS Services Delivery

Integration is currently a key factor in intelligent transportation systems (ITS), especially because of the ever increasing service demands originating from the ITS industry and ITS users. The current ITS landscape is made up of multiple technologies that are tightly coupled, and its interoperability is extremely low, which limits ITS services generation. Given this fact, novel information technologies (IT) based on the service-oriented architecture (SOA) paradigm have begun to introduce new ways to address this problem. The SOA paradigm allows the construction of loosely coupled distributed systems that can help to integrate the heterogeneous systems that are part of ITS. In this paper, we focus on developing an SOA-based model for integrating information technologies (IT) into ITS to achieve ITS service delivery. To develop our model, the ITS technologies and services involved were identified, catalogued, and decoupled. In doing so, we applied our SOA-based model to integrate all of the ITS technologies and services, ranging from the lowest-level technical components, such as roadside unit as a service (RS S), to the most abstract ITS services that will be offered to ITS users (value-added services). To validate our model, a functionality case study that included all of the components of our model was designed.

A comprehensive policy to ameliorate adverse effects of transportation facilities. Appendix.

Transportation Department, Office of the Assistant Secretary for Environment, Safety, and Consumer Affairs, Washington, D.C.

Guardrail testing program II: final report.

Federal Highway Administration, Eastern Federal Lands Highway Division, Sterling, Va.