The purpose of this study is the distribution, the emission factors, and the emission rates of the ventilation shafts of air pollutant concentration in the Hsuehshan tunnel, and analyze the correlation. The study, in the inside of Hsuehshan tunnel (the southern and the northern) and the three ventilation shafts, the real-world measure air pollutants(CO, NOx, NO, THC, NMHC and SO2) at the same time, and to analyze the concentration of air pollutants in the tunnel that is distribution of the time and spatial. In this study, the ventilation system is natural ventilation in the Hsuehshan tunnel, and the proportion of heavy vehicles in the period are less than 8%. The concentration of air pollutants in the tunnel, showing the exit higher than the entrance, the northern tunnel higher than the southern tunnel and the holidays higher than on weekdays concentration of distribution trends. The emissions and the concentration of air pollutants at the ventilation shaft No. 2 are the highest with the three shafts. All the ventilation shafts on holidays higher than weekdays were displayed on the trend of concentration distribution. The concentration of air pollutants in the tunnel are CO (12.04¡Ó1.85 ppm), THC (4.08¡Ó0.48 ppm), NMHC (2.21¡Ó0.46 ppm), NOx (1.58¡Ó0.23 ppm), NO (1.44¡Ó0.20 ppm) and SO2 (6.33¡Ó0.83 ppb). The results show that the emission factors of air pollutants in northern tunnel are higher than in southern tunnel by influence of slope. The emissions of ventilation shaft a sequence were CO, THC, and NOx. The concentrations(r¡×0.55 − 0.93) and the emission factors(r¡×0.60 − 0.96) of air pollutants are much related with traffic situation, and it shows that the air pollutants change with traffic condition. Comparison the emission factors between this study and past research in the Hsuehshan tunnel show that the air quality are becoming badly.

The Hsuehshan tunnel, whose length is about 12.9 kilometers, is the longest tunnel in Taiwan and Southeast Asia. Since the tunnel is used, it reduces the traveling time from Taipei to Ilan and brings the convenience of transportation; but the vehicles and pollution sources are added. Furthermore, the concentrations of pollutants are increased by accumulation in the long tunnel. This study estimates the effects of automobile tailpipe emissions in the Hsuehshan tunnel on the air quality of neighboring areas by using Atmospheric Dispersion Modelling System for Roads (ADMS-Roads). This work simulates carbon monoxide (CO), nitrous oxides (NOx) and sulfur dioxide (SO2) at two sites (Pin-Ling and Tou-Cheng management centers) in northern Taiwan in winter of 2008. The average concentrations of CO, NOx and SO2 at Pin-Ling (Tou-Cheng) management centers respectively are 0.49 (0.55) ppm, 10.60 (14.83) ppb and 4.80 (7.47) ppb on non-holiday and 0.66 (0.64) ppm, 16.88 (15.12) ppb and 4.70 (4.20) ppb on holiday. It shows that the concentrations of pollutants on holiday are higher than on non-holiday by increasing vehicles. Simulated results show that effects of traffic exhaust in the tunnel on the air quality of neighboring areas are less. Estimations using the ADMS-Roads suggest that the emissions are not the predominant contributors at two sites. The effect is the highest with northern (northeastern) winds at the southern (northern) area of the Hsuehshan tunnel. Comparisons between simulations and measurements at both sites are satisfactory. Simulated values are generally in agreement with measured values, with a correlation coefficient of R = 0.37 ¡V 0.81, the index of agreement (IOA) = 0.58 ¡V 0.77, and the normalized mean square error (NMSE) = 0.03 ¡V 0.25. The ADMS-Roads will be applied to assess the environmental impact while the tunnel will be allowed more types of vehicles to drive in the future.

In this study, Three-dimensional (3D) airflow and dispersion of pollutants were modeled under various excess wall temperature and traffic rate using the RNG k-£` turbulence model and Boussinesq approximation, which was solved numerically using the finite volume method. The street canyon is 60 m long (=L) and 20 m wide (=W). The height of five-story buildings on both sides of the street are about 16 m (=H). Hence, the street canyon has an aspect ratio (AR=H/W) of 0.8 and a length to width ratio of 3 (=L/W). Vehicle emissions were estimated from the measured traffic flow rates and modeled as banded line sources. 3D simulations reveal that the vortex line, joining the centers of cross-sectional vortices of the street canyon, meanders between street buildings. Notably, there is also a horizontal vortex within street canyon. Pollutant concentrations decline as the height increases, and are higher on the leeward side than on the windward side. The ratio of CO pollutants between leeward side and windward side is related to wind velocity. As wind smaller than 0.7 m/sec , the ratio is 1.23¡Fhowever, the ratio is 2.03 with more wind speed above 1.2 m/sec. The CO concentration reveals that the predicted values generally follow the hourly zigzag traffic rate, indicating that CO is closely related to the traffic emissions in a street canyon. The 3D airflow in the street canyon is dominated by both wind fields on buildings top and street exit. The 3D simulations reveal that air flux is 50% higher than 2D. Entrainment of outside air reduces pollutant concentrations, thus reducing concentrations of CO¡BNOx¡Band SO2 by about 51%¡B68% and 70% ,respectively. Thermal boundary layers are very thin. Entrainment of outside air increases and pollutant concentration decreases with increasing heating condition. For T = 5 K, the upward velocity on leeward side increases by about 10%, Also, the downward velocity on windward side decreases by about 28 %. Furthermore, simulation showed that the averaged inflow speed in the lateral direction increases by about 100% as compared with T = 0 K. Hence, the pollutant concentrations with T = 5 K is ony 50% of those without heating. Simulations are followed measurements in street canyon. The averaged simulated concentrations with no heating conditions are about 11~24% and 22~36% lower than measured for CO and NOx , respectively. For heating conditions and without outside traffic source, the averaged simulated concentrations with T = 2 K are 29~36% lower than the measurements. Even at T = 5 K , the concentrations are only about 54% of those without heating, due to the fact that pollutant dilution is enhanced by buoyancy force as to having more outside air entrained into the canyon. However, when traffic emissions outside two ends of canyon were considered, the simulated CO concentrations are 23% and 19% higher than those without outside traffic sources at T = 0 K and T = 2 K, respectively. Traffic-produced turbulence (TPT) enhances the turbulent kinetic energy and the mixing of temperature and admixtures in the canyon. Although the simulated means with the TPT effect are in better agreement with the measured means than those without the TPT effect, the average reduction of CO concentration by the TPT is only about 5% at a given height and heating conditions. Factors affecting the variations between this work and other studies are addressed and explained.

The following thesis titled, Atlanta Automotive Particulate Matter Exposure and Evaluation, presents data obtained as a part of a joint project with Emory University, Rollin's School of Public Health. The Atlanta Commuters Exposure (ACE) Study uses both real-time and time-integrated sampling techniques for ambient aerosol concentrations. The ACE study is unique in that it will correlate the ambient aerosol concentrations with the concurrent health measurements. The primary objective of this thesis is to measure the concentration, size distribution and the chemical composition of PM2.5 inside the vehicle cabin for several commuters. The vehicles followed a scripted route along roadways in the Atlanta metropolitan region during periods of peak traffic volume, while the compact air sampling package of both real-time and time-integrated instruments recorded data. Real-time measurements for Particulate Matter (PM) were made using compact Optical Particle Counters (OPC), a Condensation Particle Counter, and a MicroAethalometer. The time-integrated measurements for Elemental Carbon (EC), Organic Carbon (OC), Water Soluble Organic Carbon (WSOC), particulate elemental concentrations, and speciated organics required filter collection methods. Thus a compact air-sampling package was created to combine both sets of real-time and time-integrated instruments. The following results are presented for the first four commutes. The framework for analyzing and presenting results is developed, and will be used for future commutes.

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There is a growing public concern that emissions of mobile source air toxics (MSATs) from motor vehicles may pose a threat to human health. At present, no state or federal agencies require dispersion modeling of these compounds, but many agencies are concerned about potential future requirements. Current air pollution professionals are familiar with Federal Highway Administration (FHWA) and U.S. Environmental Protection Agency (EPA) requirements for dispersion modeling to produce predicted concentrations for comparison with appropriate standards. This research examined a method in which the potential near-road concentrations of MSATs were calculated. It was believed that by assessing MSATs in much the same way that are used for other pollutants, the model and methods developed in this research could become a standard for those quantifying MSAT concentrations near-roadways. This dissertation reports on the results from short-term (1-hour) and long-term (annual average) MSATs dispersion modeling that has been conducted on seven intersections and seven freeway segments in the state of Florida. To accomplish the modeling, the CAL3QHC model was modified to handle individual MSAT emissions input data and to predict the concentrations of several MSATs around these roadway facilities. Additionally, since the CAL3MSAT model is DOS based and not user-friendly, time was invested to develop a Windows® graphical user interface (GUI). Real-world data (traffic volumes and site geometry) were gathered, worst-case meteorology was selected, mobile source emission factors (EFs) were obtained from MOVES2010a, and worst-case modeling was conducted. Based on a literature search, maximum acceptable concentrations (MACs) were proposed for comparison with the modeled results, for both a short-term (1-hour) averaging time and a long-term (1-year) averaging time. iv Results from this CAL3MSAT modeling study indicate that for all of the intersections and freeway segments, the worst-case 1-hour modeled concentrations of the MSATs were several orders of magnitude below the proposed short-term MACs. The worst-case 1-year modeled concentrations were of the same order of magnitude as the proposed long-term MACs. The 1-year concentrations were first developed by applying a persistence factor to the worst-case 1-hour concentrations. In the interest of comparing the predicted concentrations from the CAL3MSAT persistence factor approach to other dispersion models, two EPA regulatory models (CAL3QHCR and AERMOD) with the ability to account for yearly meteorology, traffic, and signal timing were used. Both hourly and annual MSAT concentrations were predicted at one large urban intersection and compared for the three different dispersion models. The shortterm 1-hour results from CAL3MSAT were higher than those predicted by the two other models due to the worst-case assumptions. Similarly, results indicate that the CAL3MSAT persistence factor approach predicted a worst-case annual average concentration on the same order of magnitude as the two other more refined models. This indicated that the CAL3MSAT model might be useful as a worst-case screening approach.

This dissertation develops a framework for modeling vehicle emissions microscopically. In addition, the framework is utilized to develop the VT-Micro model using a number of data sources. Key input variables to the VT-Micro model include instantaneous vehicle speed and acceleration levels. Estimating accurate mobile source emissions is becoming more and more critical as a result of increasing environmental problems in large metropolitan urban areas. Current emission inventory models, such as MOBILE and EMPAC, are designed for developing large scale inventories, but are unable to estimate emissions from specific corridors and intersections. Alternatively, microscopic emission models are capable of assessing the impact of transportation scenarios and performing project-level analyses. The VT-Micro model was developed using data collected at the Oak Ridge National Laboratory (ORNL) that included fuel consumption and emission rate measurements (CO, HC, and NOx) for five light-duty vehicles (LDVs) and three light-duty trucks (LDTs) as a function of the vehicle's instantaneous speed and acceleration levels. The hybrid regression models predict hot stabilized vehicle fuel consumption and emission rates for LDVs and LDTs. The model is found to be highly accurate compared to the ORNL data with coefficients of determination ranging from 0.92 to 0.99. The study compares fuel consumption and emission results from MOBILE5a, VT-Micro, and CMEM models. The dissertation presents that the proposed VT-Micro model appears to be good enough in terms of absolute light-duty hot stabilized normal vehicle tailpipe emissions. Specifically, the emission estimates were found to be within the 95 percent confidence limits of field data and within the same level of magnitude as the MOBILE5a model estimates. Furthermore, the proposed VT-Micro model was found to reflect differences in drive cycles in a fashion that was consistent with field observations. Specifically, the model accurately captures the increase in emissions for aggressive acceleration drive cycles in comparison with other drive cycles. The dissertation also presents a framework for developing microscopic emission models. The framework develops emission models by aggregating data using vehicle and operational variables. Specifically, statistical techniques for aggregating vehicles into homogenous categories are utilized as part of the framework. In addition, the framework accounts for temporal lags between vehicle operational variables and vehicle emissions. Finally, the framework is utilized to develop the VT-Micro model version 2.0 utilizing second-by-second chassis dynamometer emission data for a total of 60 light duty vehicles and trucks. Also, the dissertation introduces a procedure for estimating second-by-second high emitter emissions. This research initially investigates high emitter emission cut-points to verify clear definitions of high emitter vehicles (HEVs) and derives multiplicative factors for newly developed EPA driving cycles. Same model structure with the VT-Micro model is utilized to estimate instantaneous emissions for a total of 36 light duty vehicles and trucks. Finally, the dissertation develops a microscopic framework for estimating instantaneous vehicle start emissions for LDVs and LDTs. The framework assumes a linear decay in instantaneous start emissions over a 200-second time horizon. The initial vehicle start emission rate is computed based on MOBILE6's soak time function assuming a 200-second decay time interval. The validity of the model was demonstrated using independent trips that involved cold start and hot start impacts with vehicle emissions estimated to within 10 percent of the field data. The ultimate expansion of this model is its implementation within a microscopic traffic simulation environment in order to evaluate the environmental impacts of alternative ITS and non-ITS strategies. Also, the model can be applied to estimate vehicle emissions using instantaneous GPS speed measurements. Currently, the VT-Micro model has been implemented in the INTEGRATION software for the environmental assessment of operational-level transportation projects. / Ph. D.