IMPROVING ASSIGNMENT RESULTS FOR AIR QUALITY ANALYSES

The hypothesis to be tested under this study was that improved 24-hour assignment results could be achieved by implementing time-of-day assignment procedures. The objectives of the study were: (1) To quantify the improvements in the 24-hour assignment results which can be obtained from using time-of-day modeling techniques in the development of 24-hour volume estimates; and (2) To measure the impact of the time-of-day modeling approach on mobile source emission estimates versus those developed using 24-hour assignment results factored to represent time-of-day volume estimates. The Houston-Galveston regional travel models and base year data were selected as the data base for this study. Neither assignment technique emerged as clearly better in replicating the count-based volume estimates. These results suggest that the users could feel equally comfortable in estimating 24-hour volumes for the Houston-Galveston region from either the four time-of-day assignments or the traditional 24-hour assignment. Likewise, neither assignment technique emerged as the better approach for developing emission estimates. There were sufficient differences in the mobile source emission estimates to suggest that the same assignment methodology should be used to compare alternatives to assure that the differences in the emission estimates would be attributable to differences in the alternatives and not to differences in the assignment methodology. Finally, a proposed set of impedance adjustment functions was developed, which is expected to produce better speed results within the assignment process for time-of-day assignments.

• Record URL:
  • https://library.ctr.utexas.edu/hostedpdfs/tti/1357-1F.pdf
• Record URL:
  • https://rosap.ntl.bts.gov/view/dot/82610
• Supplemental Notes:
  • Published November 1995; revised July 1996. Research study title: Improving Assignment Results for Air Quality Analyses.
• Corporate Authors:

  Texas Transportation Institute

  Texas A&M University System, 1600 E Lamar Boulevard
  Arlington, TX  United States  76011

  Texas Department of Transportation

  Research and Technology Transfer Office, P.O. Box 5051
  Austin, TX  United States  78763-5051

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Benson, J D
  • Borowiec, J D
• Publication Date: 1996-7

Language

• English

Media Info

• Media Type: Digital/other
• Features: References; Tables;
• Pagination: 76 p.

Subject/Index Terms

• TRT Terms: Air quality; Estimates; Periods of the day; Pollutants; Traffic assignment; Traffic volume
• Subject Areas: Environment; Finance; Highways; Operations and Traffic Management;

Filing Info

• Accession Number: 00737927
• Record Type: Publication
• Report/Paper Numbers: FHWA/TX-97/1357-1F, Res Rept 1357-1F, TTI: 0-1357 Final Report
• Contract Numbers: Study 0-1357
• Files: NTL, TRIS, ATRI, USDOT, STATEDOT
• Created Date: Jun 5 1997 12:00AM