a group of multiple motorized vehicles : airplane, train, car, bus, motocycle, express train Dr. Mikhail Chester has been developing environmental life-cycle inventories of passenger transportation modes. These analyses are the first comprehensive environmental life-cycle assessments of automobiles, buses, trains, and aircraft. The studies inventory energy consumption and emissions (greenhouse gases and conventional air pollutants) for vehicle, infrastructure, and energy productions components, from material extraction and processing through use and maintenance (well-to-wheel). Transportation Life-cycle Assessment website