@article{frey_choi_kim_2012, title={Portable Emission Measurement System for Emissions of Passenger Rail Locomotives}, ISSN={["2169-4052"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84869852000&partnerID=MN8TOARS}, DOI={10.3141/2289-08}, abstractNote={The purpose of this study was to demonstrate a method for measuring passenger railroad locomotive emissions with the use of a portable emission measurement system (PEMS) based on rail yard load tests of three locomotives, including one GP40 and two F59PHIs. These locomotives have mechanically governed diesel prime mover engines (PMEs) with an approximately 3,000-hp output. Each locomotive has a head end power (HEP) engine that produces approximately 600 hp for generating electricity used in the passenger cars. The engine measurements were based on ultralow sulfur diesel fuel. Each engine was instrumented to measure manifold absolute pressure, engine revolutions per minute, intake air temperature, and exhaust concentrations of selected gases and particles. These data were used to quantify exhaust and fuel flow. The exhaust concentrations of nitric oxide, carbon monoxide (CO), carbon dioxide, hydrocarbons, and particulate matter were measured. The PMEs are operated at each of many throttle notch settings. For the HEP engines, three electrical loads were applied on the basis of power usage for one, two, and four passenger cars, respectively. More than 97% of the raw data survived a multistep quality assurance process. The data obtained from the PEMS for the main engines were found to be comparable on a fuel basis to data reported by others, particularly for oxides of nitrogen and CO. The key results from this work are the establishment of a simplified methodology for future tests and the development of baseline data.}, number={2289}, journal={TRANSPORTATION RESEARCH RECORD}, author={Frey, H. Christopher and Choi, Hyung-Wook and Kim, Kangwook}, year={2012}, pages={56–63} }
 @article{rasdorf_frey_lewis_kim_pang_abolhassani_2010, title={Field Procedures for Real-World Measurements of Emissions from Diesel Construction Vehicles}, volume={16}, ISSN={["1943-555X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78649383748&partnerID=MN8TOARS}, DOI={10.1061/(asce)is.1943-555x.0000027}, abstractNote={Construction vehicles are a source of nonroad mobile air pollutant emissions. Emissions from construction vehicles are typically quantified based on steady-state modal engine dynamometer tests using uninstalled stationary engines. However, these tests do not represent real-world activity. Therefore, there is a need to quantify energy use and air pollutant emissions from construction vehicles based on in-use measurement methods. The purpose of this paper is to outline standard procedures for field data collection for construction vehicles. This methodology is based on second-by-second measurement of in-use activity and air pollutant emissions using a portable emissions measurement system. The field data collection methodology includes the development of a study design, installation and use of instrumentation, and field measurements. After the field data collection, the raw data undergo a quality assurance procedure to check for and correct the synchronization between the engine data and emission data. This procedure also identifies missing data and removes incorrect data. The most significant challenges to data collection include suitable weather, difficult operating conditions, and scheduling data collection sessions. Sample real-world data measurement results for a rubber tire loader are presented. The work presented here can be used as a foundational example for conducting other data collection efforts and analysis of construction vehicle emissions.}, number={3}, journal={JOURNAL OF INFRASTRUCTURE SYSTEMS}, author={Rasdorf, William and Frey, Christopher and Lewis, Phil and Kim, Kangwook and Pang, Shih-Hao and Abolhassani, Saeed}, year={2010}, month={Sep}, pages={216–225} }
 @article{frey_kim_2009, title={In-use measurement of the activity, fuel use, and emissions of eight cement mixer trucks operated on each of petroleum diesel and soy-based B20 biodiesel}, volume={14}, ISSN={["1361-9209"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-71249088383&partnerID=MN8TOARS}, DOI={10.1016/j.trd.2009.08.004}, abstractNote={Abstract In-use micro-scale fuel use and emission rates were measured for eight cement mixer trucks using a portable emission measurement system. Each vehicle was tested on petroleum diesel and B20 biodiesel. Average fuel use and emission rates increase monotonically versus engine manifold absolute pressure. A typical duty cycle includes loading at a cement plant, transit while loaded from the cement plant to work site, creeping in a queue of vehicles at the worksite, unloading, and transit without load from the site to the plant. For B20 versus petroleum diesel, there is no significant change in the rate of fuel use, CO 2 emissions, and NO emissions, and significant decreases in emissions for CO, hydrocarbons, and particulate matter. For loaded versus unloaded onroad travel, fuel use and CO 2 emissions rates are approximately 60% higher and the rates for other pollutants are approximately 30–50% higher. A substantial portion of cycle emissions occurred at the work site. Inter-vehicle and intra-cycle variability are also quantified using the micro-scale methodology.}, number={8}, journal={TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT}, author={Frey, H. Christopher and Kim, Kangwook}, year={2009}, month={Dec}, pages={585–592} }
 @article{lewis_rasdorf_frey_pang_kim_2009, title={Requirements and Incentives for Reducing Construction Vehicle Emissions and Comparison of Nonroad Diesel Engine Emissions Data Sources}, volume={135}, ISSN={["0733-9364"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-65249158552&partnerID=MN8TOARS}, DOI={10.1061/(ASCE)CO.1943-7862.0000008}, abstractNote={Nonroad construction vehicles and equipment powered by diesel engines contribute to mobile source air pollution. The engines of this equipment emit significant amounts of carbon monoxide, hydrocarbons, nitrogen oxides, and particulate matter. These pollutants pose serious problems for human health and the environment. Therefore, it is necessary to regulate and control the levels of these pollutants. Furthermore, there are emerging requirements and incentives for “greening” of construction vehicle fleets and operations. Currently, there are two types of standards that regulate air pollution for these types of vehicles: technological standards for engines and quality standards for air. It is also necessary to quantify the levels of emissions that nonroad construction vehicles and equipment produce. Quantification may be based on existing data sources (such as the EPA NONROAD model) or by collecting data directly from the vehicles as they work in the field. The purpose of this paper is to introduce the challenges to quantification of emissions from nonroad construction vehicles, describe associated governmental regulations and incentives for reducing emissions, identify and compare various sources of emissions data, establish the need to collect additional data, and propose a future research agenda that focuses on air pollution generated by construction vehicles.}, number={5}, journal={JOURNAL OF CONSTRUCTION ENGINEERING AND MANAGEMENT-ASCE}, author={Lewis, Phil and Rasdorf, William and Frey, H. Christopher and Pang, Shih-Hao and Kim, Kangwook}, year={2009}, month={May}, pages={341–351} }
 @article{frey_kim_pang_rasdorf_lewis_2008, title={Characterization of Real-World Activity, Fuel Use, and Emissions for Selected Motor Graders Fueled with Petroleum Diesel and B20 Biodiesel}, volume={58}, ISSN={["1047-3289"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-55049085635&partnerID=MN8TOARS}, DOI={10.3155/1047-3289.58.10.1274}, abstractNote={Abstract Motor graders are a common type of nonroad vehicle used in many road construction and maintenance applications. In-use activity, fuel use, and emissions were measured for six selected motor graders using a portable emission measurement system. Each motor grader was tested with petroleum diesel and B20 biodiesel. Duty cycles were quantified in terms of the empirical cumulative distribution function of manifold absolute pressure (MAP), which is an indicator of engine load. The motor graders were operated under normal duty cycles for road maintenance and repair at various locations in Wake and Nash Counties in North Carolina. Approximately 3 hr of quality-assured, second-by-second data were obtained during each test. An empirical modal-based model of vehicle fuel use and emissions was developed, based on stratifying the data with respect to ranges of normalized MAP, to enable comparisons between duty cycles, motor graders, and fuels. Time-based emission factors were found to increase monotonically with MAP. Fuel-based emission factors were mainly sensitive to differences between idle and non-idle engine operation. Cycle average emission factors were estimated for road “resurfacing”, “roading,” and “shouldering” activities. On average, the use of B20 instead of petroleum diesel leads to a negligible decrease of 1.6% in nitric oxide emission rate, and decreases of 19– 22% in emission rates of carbon monoxide, hydrocarbons, and particulate matter. Emission rates decrease significantly when comparing newer engine tier vehicles to older ones. Significant reductions in tailpipe emissions accrue especially from the use of B20 and adoption of newer vehicles.}, number={10}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Frey, H. Christopher and Kim, Kangwook and Pang, Shih-Hao and Rasdorf, William J. and Lewis, Phil}, year={2008}, month={Oct}, pages={1274–1287} }
 @article{frey_rasdorf_kim_pang_lewis_2008, title={Comparison of Real-World Emissions of B20 Biodiesel Versus Petroleum Diesel for Selected Nonroad Vehicles and Engine Tiers}, ISSN={["0361-1981"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-56749107557&partnerID=MN8TOARS}, DOI={10.3141/2058-05}, abstractNote={Field data for in-use fuel consumption and emission rates were collected for 15 nonroad vehicles by using a portable emission measurement system. Five backhoes, four front-end loaders, and six motor graders were tested once on petroleum diesel and once on B20 biodiesel. The vehicles represented a variety of engine certification tiers. A methodology was developed for study design, field data collection, data screening and quality assurance, data analysis, and benchmarking of the data. On average, 6.9% of data were lost because of quality issues and more than 3 h of valid data were collected in each test. Time-based emission factors increased monotonically with respect to engine manifold absolute pressure. Fuel-based emission factors were sensitive to differences between operations of engines idling and not idling. Typical duty cycles were quantified in terms of frequency distributions of manifold absolute pressure and used to estimate cycle average emission factors. On average, the use of B20 instead of petroleum diesel led to an insignificant 1.8% decrease in the nitric oxide (NO) emission rate and significant decreases of 18%, 26%, and 25% for opacity, hydrocarbons (HC), and carbon monoxide (CO), respectively. Emission rates decreased significantly in newer, higher-tier vehicles compared with older ones. Fuel use, NO, HC, and CO data were of similar magnitude as independent benchmark data. Specific recommendations were made for future work.}, number={2058}, journal={TRANSPORTATION RESEARCH RECORD}, author={Frey, H. Christopher and Rasdorf, William and Kim, Kangwook and Pang, Ghih-hao and Lewis, Phil}, year={2008}, pages={33–42} }