Signal Timing Optimization Models For Intersections With The Concern Of Traffic Emissions

With the development of the urbanization in China, traffic congestion and vehicle emissions in big cities have become hot spot problems in our society, but there's no so much cross field research on both traffic efficiency and green travel. Traffic control plays a key role in urban traffic efficiency. Also, the target of traffic control (i.e. vehicle) is the key link of green travel, which makes it possible for the cross field research. However, how to simultaneously guarantee the traffic efficiency and control the vehicle emissions has become one of the most important issues.Based on the previous studies of the emission factor measurements, the relationship between vehicle specific power and emission factors, and the signal timing optimization models for intersections with traffic delay, this thesis propose a new emission factor classification method, which abandon the previous emission factor classification method for dividing factors into four conditions of acceleration, deceleration, cruise and idle. In the new method, the emission factors during green and red are distinguished. This kind of classification method can link emission factors and signal timing directly, and be used as a basis of formulating the new signal timing optimization models. In the optimization models, minimizing the intersection emissions is added as an objective together with minimizing the traffic delay, which makes the model to be a bi-objective model. A new emission calculation method is developed based on the new emission factors classification method in ensuring traffic delay and traffic emission minimization.In order to systematically describe the models and methods, this paper is divided into three parts. The first part is the first chapter, in which the background and significance of this research and the domestic and foreign existing researches are analyzed and summarized. In addition, the objectives, contents and methods of this research are elaborated in this chapter. The second part is the second chapter, in which all aspects of the proposed models and methods, including the emission factor calibration, cycle and green splits optimization model, offset optimization model, and the model validation are elaborated. The results reveal that the theoretical basis and research methods are reliable. The third part is the third and the fourth chapters, in which a single intersection case and an arterial control case with signal coordination of three intersections are individually demonstrated to verify the reliability the models and methods in the second part. In this part, the calibration results of the emission factors and the optimized schemes of signal timing are obtained using the VISSIM simulation software and MATLAB programming software. Additionally, the variations of the emission factors during red and green, the optimal signal timing scheme obtained by each delay estimation formula under each level of traffic demands, and the simulation results are analyzed and comparied.The findings of this research show that the emission factors during the red and green all remain relatively stable, and the emission factors during green are always higher than those during red for the same lane group and for the same intersection, which means that the emission factor classification method is reliable. The optimized scheme obtained by using the bi-objective signal timing optimization model is identical to that obtained by using the single-objective one. The calculation and measurement results of traffic delays and vehicle emissions are close under low and medium levels of traffic demands, and in these two cases all the optimization results obtained by utilizing the HCM1985 delay model are better than those obtained by utilizing the other two models.