• Document: A Comparison Of Real-World and Modeled Emissions Under Conditions of Variable Driver Aggressiveness
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A Comparison Of Real-World and Modeled Emissions Under Conditions of Variable Driver Aggressiveness Edward K. Nam, Christine A. Gierczak, James W. Butler Ford Scientific Research Laboratory 2101 Village Road MD 3083/SRL Dearborn, MI 48121-2053 E-mail: enam@ford.com Phone: (313) 248-5833 E-mail: cgiercza@ford.com Phone: (313) 322-0140 E-mail: jbutler7@ford.com Phone: (313) 323-1729 Fax: (313) 322-7044 Submitted August 1, 2002 Word count: 4100 + 3 tables (750) + 6 figures (1500) = 6350 words TRB 2003 Annual Meeting CD-ROM Paper revised from original submittal. Nam, Gierczak, Butler 1 A Comparison Of Real-World and Modeled Emissions Under Conditions of Variable Driver Aggressiveness by E. Nam, C. Gierczak, and J. Butler Ford Scientific Research Laboratory 2101 Village Road MD 3083/ SRL Dearborn, MI 48121-2053 E-mail: enam@ford.com Phone: (313) 248-5833 ABSTRACT On-board emissions measurement techniques, or Portable Emissions Measurements Systems (PEMS), have recently become more accurate and practical, thus opening the door to many applications. In the studies described herein, a vehicle was instrumented with a PEMS developed at Ford, the Portable Real-Time Emissions Vehicle Integrated Engineering Workstation (PREVIEW), and used to measure emissions during real world driving. The emissions and travel times resulting from varying levels of driver aggressiveness were measured through a busy road network in southeast Michigan. A new quantity to measure driver behavior was defined, called “aggressivity”. In this network, it was found that aggressive driving produced significantly more emissions. In an effort to improve mobile source emissions inventory estimates, the EPA proposes to utilize PEMS to characterize in-use emissions. In this study, a microscopic traffic model (VISSIM) was integrated with the load based Comprehensive Modal Emissions Model (CMEM). An integrated microscopic traffic emissions model is practical for conducting hot spot analyses, as well as studying the effects that traffic and road changes have on air quality. The emissions model was calibrated with data acquired for the instrumented vehicle using conventional dynamometer instrumentation. A virtual vehicle was simulated in VISSIM having similar characteristics as the instrumented vehicle. The southeast Michigan road network was coded into the traffic model, into which the virtual vehicle was inserted. While the model is limited in its ability to capture second by second emissions for a relatively low emitting Tier 1 vehicle, the modeled travel time, fuel consumption and emissions fell within the range of measured values. The model was also used to quantify the relationship between emissions and aggressivity, which was used to define lower and upper bounds in comparison to the model. Despite the limitations, the combined model can be useful for many different traffic and environmental studies. TRB 2003 Annual Meeting CD-ROM Paper revised from original submittal. Nam, Gierczak, Butler 2 INTRODUCTION Numerous improvements in Portable Emissions Measurement Systems (PEMS) have opened the door for many applications where real-world in-use emissions measurements are necessary. The Environmental Protection Agency is planning to install PEMS in a sample of vehicles driven in real-world situations. The data thus obtained is to form the building blocks of the next generation mobile source emissions inventory model, called MOVES (1). The model will cover scales ranging from microscopic (intersection level) to macroscopic (region and nation). This paper is written in two parts. The first part presents the Portable Real-time Emissions Vehicle Integrated Engineering Workstation (PREVIEW), on-board, real-time, emissions measurement instrumentation developed at Ford. Emissions data from a vehicle equipped with the PREVIEW were acquired during laboratory (dynamometer) testing. The results are presented and compared to measurements from conventional dynamometer instrumentation. Real world measurements from a PREVIEW system installed on a vehicle that was driven in a section of Southfield, Michigan are also presented. Emissions, travel time, and power during "normal" and "aggressive" driving styles are compared. We define a (trip based) term “aggressivity”, which is a measure of the driver behavior mainly related to rapid speed fluctuations over a trip or driving

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