Abstract
Quantifying the fuel savings and emissions reductions that can be achieved from different truck fuel efficiency technologies for a fleet’s specific usage allows the fleet to select a combination of technologies that will yield the greatest operational efficiency and profitability. An accurate characterization of usage for the fleet, however, is critical for such an evaluation, but short-term measured drive cycle data do not generally reflect overall usage very effectively. This paper presents a detailed analysis of vehicle usage in a commercial vehicle fleet and demonstrates the development of a short duration synthetic drive cycle using measured drive cycle data collected over an extended period of time. An approach is used that matches statistical measures of the vehicle speed and acceleration history, and integrates measured grade data, to develop a compressed drive cycle that accurately represents the total usage. Drive cycle measurements obtained during a period of a full year from six tractor-trailers in normal operations in a less-than-truckload (LTL) carrier were analyzed to develop a synthetic drive cycle. The vehicle mass was also estimated to account for the variation of loads that the fleet experienced. These drive cycle and mass data were analyzed using a tractive energy analysis to quantify the fuel efficiency and CO2 emissions benefits that can be achieved on class 8 tractor-trailers when using advanced efficiency technologies, either individually or in combination. Although differences exist among class 8 tractor-trailer fleets, this study provides valuable insight into the energy and emissions reduction potential that various technologies can bring in this important trucking application. The methodology employed for generating the synthetic drive cycle serves as a rigorous approach to develop an accurate usage characterization that can be used to effectively compress large quantities of drive cycle data.
