Appraoch To Multi-level Integration Of Transportation And Emission Models On Urban Roads

The air quality has been continuously worsened by vehicle emissions from the traffic on urban roads. Nowdays, traffic management and control strategies have been increasingly recognized as an important approach to reduce emissions, which in practice require the quantitative analysis and assessment of road traffic emissions at different scales. However, transportation models and emissions models are still operationally independent in existing studies. As a result, many problems have occurred when one attempts to integrate transportation and emission models, such as inconsistent data standards, unreasonable matching parameters, insufficient descriptions of traffic operating characteristics and emissions characteristics, and the mismatch of transportation models and emissions models at different levels of traffic emissions analyses.In light of the above problems, the research in this dissertation intends to conduct studies on the the systematic integration of transportation and emissions models. To this end, it identifies the reasonable integrating parameters and explores the integrating mechanism based on the data needs for multi-level transportation and emission model integration and by standardizing the format and processing methods of traffic and emission data. The research focuses on two components, namely, (1) the description of multi-level traffic operational characteristics on urban roads for emission estimations, and (2) description of multi-level vehicle emission characteristics for transportation models.First, it reviews state-of-the-art in regards to micro-and macro-traffic operational parameters for emission estimations and emission parameters for road traffic operations. It classifies and summaries existing transportation and emission models, synthesizes existing studies on the integration of transportation and emission models, and analyzes problems of the existing research.Second, it presents the standard data format and data processing method from the perspectives of the integration of multi-level transportation and emissions models for the vehicle trajectory data, average travel speed data and second-by-second emissions data.Third, after collecting massive instantaneous vehicle trajectory data and emissions data, the relationships between transportation models and emissions models are analyzed from the perspectives of such paramenters as the average travel speed, driving cycles, speed variations, emissions factors, and emissions rates. By the analysis of the distribution characterics of the three integrating parameters, Ln(TAD), RPA, and VSP, and the analysis of their respective emissions rates for different road types and different average travel speed bins, the integration mechanism of transportation and emissions models based on the three integrating parameters is developed. The methods in describing traffic operating and emissions characteristics by the three integrating parameters, and their respective advantages and disadvantages are compared from both physical and statistical perspectives. It is shown from the analysis that VSP is a reasonable integrating parameter for the multi-level integration of transportation and emissions models. Further, the requirement for the VSP aggregation and its binning methods are analyzed for the multi-level integration of models. The multi-level mapping relationships between VSP and traffic operating parameters are subsequently established using the second-by-second vehicle trajectory data, link average travel speeds and the network traffic performance index. Ultimately, the transportation and emission integrating models are developed for specific road links and intersections, road types and the network.Finally, the research conducts three case studies:(1) the evaluation of emissions impact of different driving behavior characteristics, (2) the evaluation of emissions impact by vehicle restriction policy, and (3) the evaluation of the impact on emission factors by the traffic performance index (TPI). Results show that the proposed transportation and emission integrating models can reflect the sensitivity of the dynamic nature of traffic operating characteristics, and are capable of evaluating the impacts of different level transportation management strategies on emissions.