CARB Research Seminar

This page updated March 1, 2018

Real-World Activity of Heavy-Duty Tractors Hauling Container Chassis, Flatbed Trailer, and Tank Trailer

Photo of Thomas D. Durbin, Ph.D.

Thomas D. Durbin, Ph.D., College of Engineering Center for Environmental Research and Technology (CE-CERT), University of California, Riverside

March 27, 2018
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Research Project


The California Air Resources Board has adopted the Tractor-Trailer Greenhouse Gas (GHG) regulation to reduce GHG emissions produced by certain heavy-duty tractor-trailers. The regulation requires 53-foot or longer box-type trailers traveling in California to be equipped with aerodynamic technologies (e.g., side-skirts, front and rear trailer fairings, and undertray devices) and low-rolling resistance tires, which would result in improved fuel economy and reduced GHG emissions from the heavy-duty tractors that pull them. The Tractor-Trailer GHG regulation does not apply to other trailer types used in the freight transportation industry such as drop deck, curtain side, flatbed, tanker, bulk, dump, grain, and other trailers.
Since aerodynamic drag is proportional to the square of the vehicle operating speed, aerodynamic improvements provide the largest fuel economy and GHG benefits at high operating speeds. Thus, it is important to understand how much heavy-duty tractor-trailers travel at different operating speeds. In this study, we have collected and analyzed activity data from more than 150 heavy-duty tractors that haul container chassis, flatbed trailer, or tank trailers in California. First, we grouped the tractors that haul a specific type of trailer by their average trip distance. Then, we generated a distribution of vehicle miles traveled (VMT) in pre-defined speed bins for each group. This presentation will show the generated VMT by speed distributions, and point out the implication on potential fuel economy and GHG benefits from aerodynamic improvements for each trailer type and average distance group.

Speaker Biography

Dr. Thomas Durbin is a Research Engineer in the emissions from advanced vehicles and fuels research group of CE-CERT and an adjunct professor in the Chemical and Environmental Engineering Department. He is conducting research in the area of vehicle emissions with an emphasis on studying fuels, advanced technology vehicles, and particle and in-use emissions. This research includes programs to understand the emissions impacts of various alcohol fuels, including ethanol and butanol, biodiesel, natural gas, as well as specific fuel properties, such as sulfur content, ethanol, content, aromatics content, and olefin content, in gasoline. Dr. Durbin served as the lead researcher in a collaborative study of biodiesel emissions with the California Air Resources Board that is one of the largest studies in this area to date. Dr. Durbin is also studying the emissions rates, physical nature, composition and potential health impacts of particle emissions, as well as different methods to measure particles including low level mass methods, methods being used in Europe, and methods based on particle size. Dr. Durbin has also done extensive research in understanding ammonia and nitrous oxide emissions and has participated in the Intergovernmental Panel on Climate Change (IPCC). Dr. Durbin has also been involved in research to characterize in-use emissions and activity from construction equipment, small off-road diesel engines, marine engines, and heavy-duty trucks with laboratory grade measurements, portable emissions measurement systems (PEMS), as well as instruments that might be applicable in Inspection and Maintenance programs. More recently, this work has focused more on characterizing the performance of advanced zero/near-zero emission vehicles and technologies, including NZEV refuse haulers, ZEV yard tractors, and other vehicles and equipment.
Prior to joining the vehicle emissions group, Dr. Durbin was involved in several other areas of research at CE-CERT including renewable energy and fuel sources and advanced vehicle technologies. Tom Durbin received his doctorate degree in Physics from the University of California, Riverside, in 1994 where the primary focus of his dissertation was the study of Si films and solid lubricants.

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