Civil & Environmental Engineering
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Item ANALYSIS OF THE CONTRIBUTORY FACTORS TO THE SEVERITY OF BICYCLE, PEDAL-CYCLE, AND PEDESTRIAN RELATED CRASHES IN MARYLAND(2023) Imonitie, Livingstone; Cirillo, Cinzia; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Walking and cycling have numerous health benefits, but these popular modes of transportation are prone to numerous collisions with motor vehicles. The goal of this study is to examine some of the factors that contribute to the severity of crashes in Maryland, which include property crashes, injury crashes, and fatal crashes. The light condition, junction condition, road surface condition, lane type, road condition, road division type, weather condition, time of day, population density, and the presence of schools were all considered. To demonstrate the relationship between each variable and the severity of the crash, the ordered logistic regression model was used. According to the findings, there was a positive significant relationship between the severity of crashes and crashes that occurred in areas with no lighting, at non-intersections, and on roadways with a positive median barrier. The frequency of crashes in various regions was also influenced by population density, time of day, and the presence of schools.Item MULTI-CRITERIA VEGETATION SELECTION FOR MARYLAND BIORETENTION, WITH NITROGEN FOCUS(2015) Muerdter, Claire; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Stormwater is a leading source of nutrient pollution in natural waters. Bioretention cells can mitigate stormwater pollution. This study examines the role of vegetation in bioretention. In a bioretention field study; of Eutrochium dubium, Solidago rugosa, and Erigeron sp.; E. dubium had the thickest root and tallest aboveground biomass. The root length of the three species averaged 29.1 cm. A greenhouse bioretention mesocosm study examined three plant species: Eutrochium dubium, Iris versicolor, and Juncus effusus. Only J. effusus created significant nitrate (NO3-) removal from synthetic stormwater influent, 0.21 mg to 0.066 mg NO3--N L-1, only in low-density plantings. However, all planted treatments prevented nitrogen export vis-à-vis the unplanted treatment in two storms. J. effusus had the greatest average biomass growth of the three species, 29-fold vis-à-vis 1.3- and 2.7-fold. J. effusus is the most highly recommended plant for Maryland bioretention in this study. E. dubium is cautiously recommended.Item CATALOG OF MATERIAL PROPERTIES FOR MECHANISTIC-EMPIRICAL PAVEMENT DESIGN(2011) Li, Rui; Schwartz, Charles W.; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The new pavement design methodology is based on mechanistic-empirical principles that are expected to be used in parallel with and eventually replace the current empirical pavement design procedures. The new mechanistic-empirical pavement design guide (MEPDG) requires greater quantities and quality of input data. Material characterization for the mechanistic-empirical approach, the focus of this thesis, is significantly more fundamental and extensive than in the current empirically-based AASHTO Design Guide. The objective of the thesis is to develop an organized database of material properties for the most common paving materials used in Maryland. A comprehensive material property database in Microsoft Access 2007 has been developed. The database is initially populated with all information received from SHA. It provides complete data management tools for adding and managing future data as well as data display screens for MEPDG. Recommendations for future material testing for Maryland are also provided.Item FIELD EVALUATION OF HYDROLOGIC AND WATER QUALITY BENEFITS OF GRASS SWALES WITH CHECK DAMS FOR MANAGING HIGHWAY RUNOFF(2009) Jamil, Nor Eliea Eluziea; Davis, Allen P; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)ABSTRACT Title of Thesis: FIELD EVALUATION OF HYDROLOGIC AND WATER QUALITY BENEFITS OF GRASS SWALES WITH CHECK DAMS FOR MANAGING HIGHWAY RUNOFF Nor Eliea Eluziea Jamil, Master of Science, 2009 Thesis Directed By: Professor Allen P. Davis Departrment of Civil and Environmental Engineering Managing highway runoff is a complex storm water management problem. This research is an input/output field study that specifically examines the hydrologic and water quality benefits of having grass swales with an additional pre-treatment area and incorporation of check dams for managing highway runoff at a Maryland highway. These swales manage the hydrology of the stormwater by increasing the lag time (2-3 hours), reducing the overall average peak (32-44%) and reducing the total runoff volume (4-46%). The overall mass pollutant loads are reduced for TSS (38-62%), nitrate (92-95%), nitrite (54-71%), lead (78-82%), copper (56-70%) and zinc (67-79%). On the other hand, TKN (-120 to 44%), TP (-5 to 40%) and chloride (-61 to -4%) show mass increase. Compared to previous study, swales with check dams do not show any significant improvement over swales without check dams. However, a check dam swale with a pretreatment area has higher reduction of the overall mass pollutants removal for all pollutants except for TSS.Item Evaluation of Nitrogen Nonpoint-source Loadings using High Resolution Land Use Data in a GIS: A Multiple Watershed Study for the State of Maryland.(2008-08-14) Ahmed, Sarah Naveed; Moglen, Glenn E; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The performance of three monitoring perspectives, for the detection of watershed compliance with water quality standards, was evaluated. In order to compare performances 35 watershed nonpoint-source nitrogen loading cases were calculated within a GIS. Calculations showed that the probability of loads exceeding a criterion at the watershed outlet is more representative of upstream conditions than a nominal mean load comparison at the watershed outlet. Combined outlet compliance interpretations were found to isolate loading conditions that on average did not exceed the criterion; however, variations within loading distributions were large such that compliant conditions were threatened. The whole watershed perspective mapped the relationship between stream network structure, land cover/land use, and loadings. Comparisons between the perspectives suggested that both outlet perspectives usually are consistent with whole watershed conditions. Semivariograms were demonstrated to characterize spatial variability in loadings and predict the accuracy with which monitoring sites represent loads at upstream locations.Item Examination of a GIS-Based Water Quality Model using USGS Gaged Watersheds in Maryland(2007-06-13) Shivers, Dorianne E.; Moglen, Glenn E; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Water quality models are important tools used by the Maryland Department of the Environment (MDE) in developing Total Maximum Daily Loads (TMDLs), which serve as water quality standards. The MDE tool, which spatially interpolates output from the Chesapeake Bay Program Watershed Model (WSM), is often used because it requires little time, data, or training. In contrast, the WSM requires extensive time, data, and training to run. This study examines if the MDE tool provides accurate estimates of pollutant loads and whether the mid-level complexity model AVGWLF provides comparatively more accurate estimates. The accuracy of the models was assessed based on qualitative comparisons, t-tests, and Nash-Sutcliffe coefficients. The MDE tool was found to more accurately predict total nitrogen and total sediment loads and the AVGWLF model was found to more accurately predict total phosphorus loads. The study also found that a consistent method for calculating observed loads needs to be developed.