As the air pollution problem in the major metropolitan areas of the United States has increased, new interest has emerged for greater accuracy in the estimation of emissions from mobile sources. Gridded emissions estimates owing to vehicular travel are generally produced from roadway travel data generated by transportation planning models, but the transportation planning models have generally been designed and used by transportation analysts to evaluate the effects of increased development on roadway level of service and to determine roadway capacity needs for a local or regional area and are not always ideally suited to support gridded mobile source emissions development. The results of a new methodology that significantly enhances the emissions prediction capability of regional travel models are reported. The methodology was developed for the eight counties in the San Joaquin Valley of California. Most transportation models produce travel estimates only on an average basis and only for average weekday conditions. The levels of vehicle travel vary significantly by hour throughout the day and from weekdays to weekends as well. When investigating hour-specific air quality episodes that result from pollutant or precursor emissions generated during previous hours, this poor temporal resolution of the transportation model severely lowers the accuracy of the hourly estimated mobile source inventory. The methodology discussed includes combining regional forecasts with supplemental traffic count data on time-of-day and vehicle type distribution of travel to improve the temporal resolution of the model-based travel activity data.


  • English

Media Info

  • Features: Figures; Tables;
  • Pagination: p. 145-154
  • Monograph Title: Transportation environmental issues: air, noise, water, mitigation processes, and alternative fuels
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00674211
  • Record Type: Publication
  • ISBN: 0309060508
  • Files: TRIS, TRB, ATRI
  • Created Date: Jan 31 1995 12:00AM