@article{sandhu_frey_bartelt-hunt_jones_2016, title={Real-world activity, fuel use, and emissions of diesel side-loader refuse trucks}, volume={129}, ISSN={["1873-2844"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84957899410&partnerID=MN8TOARS}, DOI={10.1016/j.atmosenv.2016.01.014}, abstractNote={Diesel refuse trucks have the worst fuel economy of onroad highway vehicles. The real-world effectiveness of recently introduced emission controls during low speed and low engine load driving has not been verified for these vehicles. A portable emission measurement system (PEMS) was used to measure rates of fuel use and emissions on six side-loader refuse trucks. The objectives were to: (1) characterize activity, fuel use, and emissions; (2) evaluate variability between cycles and trucks; and (3) compare results with the MOVES emission factor model. Quality assured data cover 210,000 s and 550 miles of operation during which the trucks collected 4200 cans and 50 tons of waste material. The average fuel economy was 2.6 mpg. Trash collection contributed 70%–80% of total fuel use and emissions. The daily activity Operating Mode (OpMode) distribution and cycle average fuel use and emissions is different from previously used cycles such as Central Business District (CBD), New York Garbage Truck (NYGT), and William H. Martin (WHM). NOx emission rates for trucks with selective catalytic reduction were over 90% lower than those for trucks without. Similarly, trucks with diesel particulate filters had over 90% lower particulate matter (PM) emissions than trucks without. Compared to unloaded trucks, loaded truck averaged 18% lower fuel economy while NOx and PM emissions were higher by 65% and 16%, respectively. MOVES predicted values are highly correlated to empirical data; however, MOVES estimates are 37% lower for NOx and 300% higher for PM emission rates. The data presented here can be used to develop more representative cycles and improve emission factors for side-loader refuse trucks, which in turn can improve the accuracy of refuse truck emission inventories.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Sandhu, Gurdas S. and Frey, H. Christopher and Bartelt-Hunt, Shannon and Jones, Elizabeth}, year={2016}, month={Mar}, pages={98–104} }
 @article{sandhu_frey_bartelt-hunt_jones_2015, title={In-use activity, fuel use, and emissions of heavy-duty diesel roll-off refuse trucks}, volume={65}, ISSN={["2162-2906"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84942103066&partnerID=MN8TOARS}, DOI={10.1080/10962247.2014.990587}, abstractNote={The objectives of this study were to quantify real-world activity, fuel use, and emissions for heavy duty diesel roll-off refuse trucks; evaluate the contribution of duty cycles and emissions controls to variability in cycle average fuel use and emission rates; quantify the effect of vehicle weight on fuel use and emission rates; and compare empirical cycle average emission rates with the U.S. Environmental Protection Agency’s MOVES emission factor model predictions. Measurements were made at 1 Hz on six trucks of model years 2005 to 2012, using onboard systems. The trucks traveled 870 miles, had an average speed of 16 mph, and collected 165 tons of trash. The average fuel economy was 4.4 mpg, which is approximately twice previously reported values for residential trash collection trucks. On average, 50% of time is spent idling and about 58% of emissions occur in urban areas. Newer trucks with selective catalytic reduction and diesel particulate filter had NOx and PM cycle average emission rates that were 80% lower and 95% lower, respectively, compared to older trucks without. On average, the combined can and trash weight was about 55% of chassis weight. The marginal effect of vehicle weight on fuel use and emissions is highest at low loads and decreases as load increases. Among 36 cycle average rates (6 trucks × 6 cycles), MOVES-predicted values and estimates based on real-world data have similar relative trends. MOVES-predicted CO2 emissions are similar to those of the real world, while NOx and PM emissions are, on average, 43% lower and 300% higher, respectively. The real-world data presented here can be used to estimate benefits of replacing old trucks with new trucks. Further, the data can be used to improve emission inventories and model predictions. Implications: In-use measurements of the real-world activity, fuel use, and emissions of heavy-duty diesel roll-off refuse trucks can be used to improve the accuracy of predictive models, such as MOVES, and emissions inventories. Further, the activity data from this study can be used to generate more representative duty cycles for more accurate chassis dynamometer testing. Comparisons of old and new model year diesel trucks are useful in analyzing the effect of fleet turnover. The analysis of effect of haul weight on fuel use can be used by fleet managers to optimize operations to reduce fuel cost.}, number={3}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Sandhu, Gurdas S. and Frey, H. Christopher and Bartelt-Hunt, Shannon and Jones, Elizabeth}, year={2015}, month={Mar}, pages={306–323} }
 @article{sandhu_frey_bartelt-hunt_jones_2014, title={In-use measurement of the activity, fuel use, and emissions of front-loader refuse trucks}, volume={92}, ISSN={["1873-2844"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84901001305&partnerID=MN8TOARS}, DOI={10.1016/j.atmosenv.2014.04.036}, abstractNote={Field measurements were made for six front-loader refuse trucks for over 560 miles (901 km) and 47 h of operation using a portable emissions measurement system, electronic control unit data logger, and global positioning system receivers. Daily activity, fuel use rates, and emission rates are quantified in terms of operating mode bins defined by the U.S. Environmental Protection Agency for the MOVES emission factor model. On average, 44 (±4) percent of time was spent at idle, 5 (±1) percent braking or decelerating, 11 (±2) percent coasting, 23 (±3) percent cruising or accelerating at low speed (up to 25 mph, 40.2 kmph), 10 (±2) percent cruising or accelerating at moderate speed (25–50 mph, 40.2 to 80.4 kmph), and 7 (±3) percent cruising or accelerating at high speed (50 mph, 80.4 kmph or higher). Fuel use and emission rates varied among operating modes by factors of 6–24. The estimated daily activity cycle average fuel economy ranges from 2.3 to 3.2 mpg (0.98–1.4 kmpl). The PM emission rates for trucks with diesel particulate filters are 98 percent lower compared to those without. Variation in truck weight lead to differences in average fuel use and emission rates of 20 percent or less, except for hydrocarbons. The variation in the empirically-based daily activity cycle average rates were highly correlated with MOVES estimates, except for hydrocarbons. The data collected here are useful for quantifying daily activity specific to front-loaders, and for developing fuel use and emission estimates and models for this type of vehicle.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Sandhu, Gurdas S. and Frey, H. Christopher and Bartelt-Hunt, Shannon and Jones, Elizabeth}, year={2014}, month={Aug}, pages={557–565} }
 @article{hu_frey_sandhu_graver_bishop_schuchmann_ray_2014, title={Method for Modeling Driving Cycles, Fuel Use, and Emissions for Over Snow Vehicles}, volume={48}, ISSN={["1520-5851"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84904409293&partnerID=MN8TOARS}, DOI={10.1021/es501164j}, abstractNote={As input to a winter use plan, activity, fuel use, and tailpipe exhaust emissions of over snow vehicles (OSV), including five snow coaches and one snowmobile, were measured on a designated route in Yellowstone National Park (YNP). Engine load was quantified in terms of vehicle specific power (VSP), which is a function of speed, acceleration, and road grade. Compared to highway vehicles, VSP for OSVs is more sensitive to rolling resistance and less sensitive to aerodynamic drag. Fuel use rates increased linearly (R2>0.96) with VSP. For gasoline-fueled OSVs, fuel-based emission rates of carbon monoxide (CO) and nitrogen oxides (NOx) typically increased with increasing fuel use rate, with some cases of very high CO emissions. For the diesel OSVs, which had selective catalytic reduction and diesel particulate filters, fuel-based NOx and particulate matter (PM) emission rates were not sensitive to fuel flow rate, and the emission controls were effective. Inter vehicle variability in cycle average fuel use and emissions rates for CO and NOx was substantial. However, there was relatively little inter-cycle variation in cycle average fuel use and emission rates when comparing driving cycles. Recommendations are made regarding how real-world OSV activity, fuel use, and emissions data can be improved.}, number={14}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Hu, Jiangchuan and Frey, H. Christopher and Sandhu, Gurdas S. and Graver, Brandon M. and Bishop, Gary A. and Schuchmann, Brent G. and Ray, John D.}, year={2014}, month={Jul}, pages={8258–8265} }
 @article{sandhu_frey_2013, title={Effects of errors on vehicle emission rates from portable emissions measurement systems}, number={2340}, journal={Transportation Research Record}, author={Sandhu, G. S. and Frey, H. C.}, year={2013}, pages={10–19} }
 @article{boroujeni_frey_sandhu_2013, title={Road Grade Measurement Using In-Vehicle, Stand-Alone GPS with Barometric Altimeter}, volume={139}, ISSN={["0733-947X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84881240089&partnerID=MN8TOARS}, DOI={10.1061/(asce)te.1943-5436.0000545}, abstractNote={Real-world vehicle fuel use and emission rates are sensitive to road grade. There is a need for a practical method for measuring road grade in combination with on-board measurement of vehicle activity, energy use, and emissions using portable emissions measurement systems (PEMS). This paper focuses on quantification of the accuracy and precision of a low-cost method using a stand-alone global positioning system (GPS) receiver with an in-built barometric altimeter. Approximately 100 one-way runs were made on each of several study routes. The sensitivity of average grade estimates to the averaging distance over which grade is estimated is quantified. The repeatability of vehicle location and distance traveled is quantified. The run-to-run variability and confidence intervals for average estimates of grade are quantified. The accuracy of the grade estimates is evaluated in comparison to LIDAR-based estimates. The low-cost method is shown to be accurate, but imprecision in the measurements leads to a need for typically at least 10 or more repeated runs, depending on the desired precision of the average estimate of grade.}, number={6}, journal={JOURNAL OF TRANSPORTATION ENGINEERING-ASCE}, author={Boroujeni, Behdad Yazdani and Frey, H. Christopher and Sandhu, Gurdas Singh}, year={2013}, month={Jun}, pages={605–611} }
 @article{sandhu_frey_2012, title={Real-world measurement and evaluation of duty cycles, fuels, and emission control technologies of heavy-duty trucks}, number={2270}, journal={Transportation Research Record}, author={Sandhu, G. S. and Frey, H. C.}, year={2012}, pages={180–187} }