The Environmental Protection Agency's (EPA) newest emission model includes driving cycles that were constructed using chase car data collected in three cities. This data is then organized by facility and level of service (LOS) to eliminate regional variability in driving. This approach to driving cycle construction presumes that regional driving variability is insignificant when controlling for facility type and LOS. The present study reconsiders the issue of regional driving variability and its potential impact on emissions using driving data collected in the San Francisco Bay Area, Sacramento and Stanislaus, California. Regional driving characteristics are examined for four types of driving conditions: uncongested and congested freeway driving, and uncongested and congested arterial driving. The results suggest regional similarities in terms of the average speeds and accelerations, but marked differences in frequency, duration and intensity of both steady state and acceleration modal events. A one-way analysis of variance indicates that regional driving variability exists even after controlling for LOS and facility type. A new method for constructing driving cycles shows how regional differences can result in driving cycles with significantly different composition of modal events (i.e., cruise, idle, acceleration and deceleration). An examination of the cycles with respect to steady state driving and acceleration/deceleration modal events confirms that regional driving differences are large enough to result in important driving cycle differences. These regional differences should be taken into consideration when constructing emission models.


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  • Accession Number: 00961877
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 28 2003 12:00AM