conference paper
published journal article
This article explores ways in which land use policy outcomes vary across contexts focusing, as an example, on urban growth boundaries. Specifically, it analyzes how various contextual factors interact with the policy and generate diverging development outcomes by employing a kernel-based regularized least squares method. Results show that the policy effectiveness is largely dependent on the region’s population size, initial density levels, and organizational conditions. The presence of urban growth boundaries also appears to shape the way other determinants influence development patterns, suggesting that the policy can both directly and indirectly promote a more compact/contiguous pattern of development.
conference paper
Most,discrete choice models assume steady state conditions and a fully equilibrated system when estimating unknown coefficients from real-world data. However, the estimated model can be biased when the data set used for the model estimation was drawn from non- or less-equilibrated traveler behavior. The resulting biased model could lead to a misunderstanding of the system. Such effects on discrete choice model estimation were examined by performing Monte Carlo simulation experiments. A day-to-day dynamic evolutionary framework was used to observe changes in traveler’s choice and to compare the estimated results during the adjustment process with the true behavior parameters.
published journal article
conference paper
published journal article
Recent literature has shown that volatile organic compound (VOC) emission inventories for urban regions may be substantially underestimated. In particular, non-transportation sources including volatile chemical products (VCP) are increasing in relative importance due to both the current and historical focus on controlling transportation emissions. These findings have major implications for photo-chemical air quality modeling used to determine appropriate and effective regulatory controls to meet limits for primary and secondary pollutants. Using a regional air quality model, we quantify the changes in ozone and fine particulate matter (PM2.5) simulated for updated VOC emissions reported in the recent literature relative to a baseline inventory for California. Results show that simulated maximum 8-hr ozone concentrations could increase by 17.4 ppb in summer and by 15.6 ppb in winter, and the 24-hr maximum PM2.5 could increase by 7.8 mu g/m(3) in winter. Impacts reflect differences in the spatial location of VCP source emissions relative to those for transportation. However, compared to measurement data, model performance is not substantially improved by the adjustment of VOC emissions of current sources. In brief, augmented VOC emission inventories impact simulated concentrations of pollutants, but may not improve the performance of models used for the design of emission control policy without more refined representation of missing VCPs sources in the inventory.
conference paper
A new framework for inter-regional commodity flow forecasting is presented to improve estimates of freight demand for inter-regional and statewide transportation models. The Structural Equations for Multi-Commodity OD Distribution (SEMCOD) model is based on simultaneous direct demand equations with structural relationships between dependent and independent variables of the model. SEMCOD is a flexible model that integrates the generation and distribution steps in conventional four-step demand models. This integration provides consistent estimates for elasticity analysis of effective factors for freight flows at the OD level and for productions and attractions at the zone level. Also, the model is sensitive to policies that increase or decrease generalized transportation cost, not only for flow distribution but also by measuring the change in marginal production and attraction of each zone. Unlike gravity-type models, this framework provides the opportunity to identify homogenous clusters of ODs and to more accurately estimate parameters for each cluster. The proposed model is estimated using the Freight Analysis Framework (FAF3) and other publicly available data sources for 15 commodity groups. Elasticity of different factors on production, attraction and flow of different commodity groups with respect to industry specific employment, population, industrial GDP, variables related to consumption and production of energy and land use variables, are studied. Considering cross relationships between supply chains of different commodity groups in the model significantly improved the fitness of the model. The fitness measures confirm satisfactory performance of the model.
published journal article
published journal article
published journal article