Analysis Of Differences Of Driving Behaviors In Cities Of Different Sizes And Their Effects On Emissions

With the accelerated urbanization,the vehicle population continues to increase rapidly.Such a progress brings convenience to people’s lives,while at the same time directly leads to increasingly worsened traffic congestion and vehicle emission problems.These negative effects are hindering the sustainable development of cities.As a typical first-tier city in China,Beijing has deeply been troubled by such negative impacts.In the past few decades,Beijing has invested substantial amount of time and resources to deal with the severe pollution problems,implemented a series of powerful and effective energy-saving and emission reduction measures,and accumulated many important and valuable experiences.For a typical fourth-tier city like Xuchang,the strategy on the transportation energy conservation and emission reduction is still in the exploratory stage.Such a city can practically draw the valuable experiences accumulated and lessons learned by the first-tier cities like Beijing in the development of various implementable strategies.In addition,with the development of intelligent transportation systems,the topics such as driving behavior,traffic safety,and traffic emissions have become evolving research areas of scholars.Many studies have been conducted on traffic emissions for a single city,but few studies have been found on the comparison of traffic emissions between cities of different sizes.In order to fill this research gap,this thesis is intended to study the differences of driving behaviors in cities of different sizes and their effects on emissions based on the vehicle trajectory data collected from cities of different sizes.The research is conducted by:（1）carrying out the research on the emission differences of cities of different sizes from the operating parameters of the motor vehicles and（2）conducting the research on the emission differences of the same driving style category in cities of different sizes in order to study the possibility of using massive data collected from the mega city to the emission analysis for small and mid-sized cities.The thesis selected Beijing and Xuchang,representing two typical cities of different sizes,to pursue its studies.First,it established VSP（Vehicle Specific Power）distributions of the two cities and then calculated the emission differences based on the VSP distributions.Second,it established VSP distributions of expressway,main arterial,minor arterial and streets in Beijing and Xuchang,and calculated the respective emission differences for different road types between the two cities.Finally,it carried out the driving behavior analysis using a sample size of 86 vehicles from the two cities,establishing VSP distributions under categories of conservative versus ordinary driving types,resulting in an analysis of the emission differences of two different driving behaviors in Beijing and Xuchang.The research in the thesis has found that the overall VSP of cities of different sizes is quite consistent with the mean VSP overlap rate greater than 91.8%.The differences of the four pollutant emissions,CO,CO₂,NOx,and HC,are 11.9%,4.79%,10.92%,16.16%,respectively.This means that the data collected from the mega city can be reasonably used to establish the VSP distributions for small and mid-sized cities.The overlap rates of VSP distributions on various road types,expressway,main arterial,minor arterial,and streets,between the two cities are 76.57%,91.50%,85.73%,and87.56%,with the mean VSP overlap rates of 85.13%,94.26%,92.64%,and 88.5%respectively.The emission differences of the four pollutant emissions are 31.6%,20.1%,26.46%and 36.24%respectively.The average VSP overlap rate of conservative driving type in the two cities is 94.45%,while the ordinary type is 71.6%.The emission differences of the conservative versus ordinary driving types of the two cities are about17.9%and 46.84%,respectively,which shows that emission differences of conservative driving type in cities of different sizes is smaller,thus the conservative driving type data from the mega city can potentially be used for alternative analysis for small and mid-sized cities.