Work zone tends to cause hazardous conditions for drivers and construction workers since work zones generate conflicts between construction activities and the traffic, therefore aggravate the existing traffic conditions and result in severe traffic safety and operational problems. To address the influence of various factors on the crash severity is beneficial to understand the characteristics of work zone crashes. The understanding can be used to select proper countermeasures for reducing the crash severity at work zones and improving work zone safety. In this dissertation, crash severity models were developed to explore the factor impacts on crash severity for two work zone crash datasets (overall crashes and rear-end crashes). Partial proportional odds logistic regression, which has less restriction to the parallel regression assumption and provides more reasonable interpretations of the coefficients, was used to estimate the models. The factor impacts were summarized to indicate which factors are more likely to increase work zone crash severity or which factors tends to reduce the severity. Because the speed variety is an important factor causing accidents at work zone area, the work zone speed profile was analyzed and modeled to predict the distribution of speed along the distance to the starting point of lane closures. A new learning machine algorithm, support vector regression (SVR), was utilized to develop the speed profile model for freeway work zone sections under various scenarios since its excellent generalization ability. A simulation-based experiment was designed for producing the speed data (output data) and scenario data (input data). Based on these data, the speed profile model was trained and validated. The speed profile model can be used as a reference for designing appropriate traffic control countermeasures to improve the work zone safety.

華人社會傳承了儒家文化思想的價值觀，但是在社會環境、政治體制及人口結構等因素的差異之下，衍生出各種文化特性的差異。本研究使用世界價值觀調查（World Values Survey，WVS）資料，比較不同社會中的華人在文化特性方面的差異，並分析文化特性及其他因素對主觀福祉（subjective well-being）的影響。 本研究採用世界價值觀調查所建立之社會價值觀（societal values），加入其他文化特徵、社會態度及個人生活觀衡量文化特性。本研究使用之計量模型為排序羅吉特迴歸（ordered logit regression）模型，分析上述變數對華人生活滿意度（life satisfaction）與快樂程度（happiness）的影響。本研究之目的在於找出影響華人主觀福祉之重要決定因素，並探討文化因素在收入與主觀福祉之間是否存在調節效果（moderating effect）。 實證結果顯示，文化會影響華人主觀福祉，並在收入與主觀福祉之間造成調節效果。而華人在各個社會中所衍生出的文化特性差異，也使得各個社會中華人主觀福祉的重要決定因素有所差異。 / Chinese societies inherited the values of Confucianism. However, these societies vary in their social environment, political system and demographic structure, thus result in differences in their cultural characteristics. This study uses the data from World Values Survey, to explore the differences among Chinese in different societies, and to analyze the determining factors of Chinese subjective well-being. In this study, the societal values established by the World Values Survey are used to represent the cultural properties. We also added other cultural traits, social attitudes and individual viewpoints for our analysis. In this study, we use ordered logit regression model to find out the important determinants of Chinese subjective well-being in different societies, and discuss whether there exists a cultural moderating effect between income and subjective well-being. Empirical results show that culture has a significant impact on subjective well-being of Chinese, and the effect of income on Chinese subjective well-being are also moderated by cultural properties. The differences between these Chinese societies also result in divergences of important determinants of Chinese subjective well-being between societies.