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Raleigh, NC, United States

Lai X.,Rummel | Schonfeld P.,University of Maryland University College
Transportation Research Record

Urban rail transit systems are being extended throughout the world because of their large capacities, avoidance of traffic congestion, and environmental advantages. Various optimization models can help design rail transit alignments satisfying various track geometry constraints, but none of these models can account for the impacts of vehicle dynamics on operational and user costs. This paper presents a practical rail transit alignment optimization method for designing track alignments that accounts for vehicle dynamics. The method can generate alignments that improve the balance between the initial cost and the operation and user costs recurring throughout the system's life cycle. A heuristic based on a genetic algorithm is developed to search for solutions efficiently while interacting with the supporting geographic information system. A hypothetical topography scenario is created to illustrate the impact of vehicle dynamics on the trade-offs among system costs. The Baltimore, Maryland, Red Line is used as a case study to demonstrate that the model can find good solutions in regions with complex topographies. Source

Marshall S.K.,Rummel | Marshall S.K.,North Carolina State University | Rasdorf W.,North Carolina State University | Lewis P.,Oklahoma State University | Frey H.C.,North Carolina State University
Journal of Architectural Engineering

Construction of commercial buildings has an environmental impact because of emissions from nonroad equipment. Construction produces 7% of the U.S. greenhouse gas emissions, of which 76% originates from engines. However, there has not been an established methodology for estimating construction activity emissions at the project level for buildings and other constructed facilities. Therefore, determining where and when construction produces emissions is important, necessitating that emissions inventories (i.e., databases of project emissions by type, cost, etc.) be developed to quantify these emissions. The pollutants addressed in this paper include carbon dioxide (CO2), nitrogen oxides (NOx), total hydrocarbons (THC), carbon monoxide (CO), particulate matter (PM), and sulfur dioxide (SO2). This paper presents a methodology that provides a direct link between building construction activities and emissions. The use of this methodology is demonstrated for a commercial building case study, thereby providing quantified emissions predictions for various levels of detail (i.e., construction activity, construction cost division, and overall project). Using this methodology, both fuel use and emissions can be determined at any stage of the planning, designing, and building process with increasing levels of precision being obtained as the project progresses. The methodology demonstrates the ability to link key quantitative indicators of specific building construction activities to emission rates for specific types of equipment used in construction. The case study results illustrate that emissions during construction are highly episodic, with site work activities and equipment contributing large proportions of overall project emissions. © 2012 American Society of Civil Engineers. Source

Zaya D.N.,University of Illinois at Chicago | Leicht-Young S.A.,Rummel | Pavlovic N.B.,U.S. Geological Survey | Feldheim K.A.,Pritzker Laboratory for Molecular Systematics and Evolution | Ashley M.V.,University of Illinois at Chicago
Biological Invasions

Hybridization associated with species introductions can accelerate the decline of native species. The main objective of this study was to determine if the decline of a North American liana (American bittersweet, Celastrus scandens) in the eastern portion of its range is related to hybridization with an introduced congener (oriental bittersweet, C. orbiculatus). We used newly characterized microsatellite loci, a maternally-inherited chloroplast DNA marker, and field observation to survey individuals across the USA to determine the prevalence of hybrids, their importance in the invasion of C. orbiculatus, and the predominant direction of hybridization. We found that only 8.4 % of non-native genotypes were hybrids (20 of 239), and these hybrids were geographically widespread. Hybrids showed reduced seed set (decline of >98 %) and small, likely inviable pollen. Genetic analysis of a maternally inherited chloroplast marker showed that all 20 identified hybrids came from C. scandens seed parents. The strong asymmetry in pollen flow that favors fecundity in introduced males has the potential to greatly accelerate the decline of native species by wasting limited female reproductive effort. © 2015, Springer International Publishing Switzerland. Source

Rasdorf W.,North Carolina State University | Lewis P.,Oklahoma State University | Marshall S.K.,Rummel | Arocho I.,North Carolina State University
Proceedings, Annual Conference - Canadian Society for Civil Engineering

Construction operations are heavy users of nonroad equipment and diesel engines. These engines are large contributors of CO 2 and consume large quantities of diesel fuel. This paper utilizes a case study to quantify CO 2 and fuel use on a construction project and to determine when these occur. The paper links construction project activity emissions and fuel use with a project schedule to establish a temporal relationship. RS Means was used to obtain equipment productivity. Equipment CO 2 emission and fuel use rates were obtained from EPA's NONROAD model. A sensitivity analysis was conducted to investigate the impact of changes in scheduling on CO 2 production and fuel use. Site construction activities proved to cause a significant spike in emissions early in the project. Fuel use closely tracked the CO 2 production when compared via a cumulative frequency diagram. The methodology discussed here can be readily used by construction and environmental professionals to estimate fuel use and CO 2 emissions for various commercial construction projects. Source

Rummel | Date: 1999-02-05

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