• Developing Guidelines for Two-Dimensional Model Review and Acceptance

      Toniolo, Horacio; Homan, Joel (Center for Environmentally Sustainable Transportation in Cold Climates, 2018-01-31)
      Two independent modelers ran two hydraulic models, SRH-2D and HEC-RAS 2D. The models were applied to the Lakina River (MP 44 McCarthy Road) and to Quartz Creek (MP 0.7 Quartz Creek Road), which approximately represent straight and bend flow conditions, respectively. We compared the results, including water depth, depth averaged velocity, and bed shear stress, from the two models for both modelers. We found that the extent and density of survey data were insufficient for Quartz Creek. Neither model was calibrated due to the lack of basic field data (i.e., discharge, water surface elevation, and sediment characteristics). Consequently, we were unable to draw any conclusion about the accuracy of the models. Concerning the time step and the equations used (simplified or full) to solve the momentum equation in the HEC-RAS 2D model, we found that the minimum time step allowed by the model must be used if the diffusion wave equation is used in the simulations. A greater time step can be used if the full momentum equation is used in the simulations. We developed a set of guidelines for reviewing model results, and developed and provided a two-day training workshop on the two models for ADOT&PF hydraulic engineers.
    • Modeling Impacts of Cold Climates on Vehicle Emissions

      Chung, Serena (Center for Environmentally Sustainable Transportation in Cold Climates, 2017-01-20)
      This project relates to the research thrust area of ‘environmental impact assessment,' specifically the impact of cold climates on vehicle exhaust emissions. Motor vehicles emit pollutants that are harmful to human. Emissions are thought to be elevated during engine cold starts. During winter, low-lying temperature inversion can trap vehicle emissions near the surface, leading to significantly elevated pollutant concentrations. Despite the importance, vehicle emissions data for cold climates are sparse and the accuracy of vehicle emissions model parameterizations for cold climates is not known. The goal of this project is to improve ability of EPA's Motor Vehicle Emission Simulator (MOVES) model to simulate cold start emissions in cold climates