The emissions factor modeling component of the motor vehicle emissions inventory (MVEI) modeling suite is currently being revised by the California Air Resources Board (CARB). One of the proposed changes in modeling philosophy is a shift from using link-based travel activity data to trip-based travel data for preparing mobile emissions inventories. New speed correction factors (SCFs) will also be developed by CARB for the revised model. The new SCFs will be derived from vehicle emissions on 15 new driving cycles, each constructed to represent a typical trip at a specific average speed. This paper discusses how the new SCFs will affect transportation conformity and emissions inventory development, and evaluates the differences in total emissions produced by trip- and link-based distributions of speed and vehicle miles of travel (VMT). Both the link- and the trip-based speed-VMT distributions were simulated using travel data from the Sacramento and San Diego travel demand models. Results indicate that there is reason to expect that mobile emissions inventories constructed using the proposed trip-based philosophy will differ markedly from those constructed in the current manner. Increases are expected in the CO and HC inventory levels, with concomitant decreases in the NO sub(x) mobile emissions inventories.

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  • Corporate Authors:

    Air & Waste Management Association

    One Gateway Center, 3rd Floor, 420 Fort Duquesne Boulevard
    Pittsburgh, PA  United States  15222
  • Authors:
    • Nanzetta, K
    • Niemeier, D
    • Utts, J M
  • Publication Date: 2000-3


  • English

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Filing Info

  • Accession Number: 00798701
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 11 2000 12:00AM