Link-Based Calculation of Motor Vehicle Air Toxin Emissions Using Mobile 6.2

The U.S. Environmental Protection Agency's (EPA’s) MOBILE 6.2 model allows transportation planners to respond to community concerns by calculating air toxin emissions from motor vehicles. Metro partnered with EPA, ICF Consulting, and the Oregon Department of Environmental Quality in estimating emissions of 27 hazardous air pollutants at the link and zone level. This presentation describes the emission calculation algorithms that Metro developed for use in EMME/2, MOBILE, Stata, and Oracle. The chosen approach involved splitting daily vehicle volumes into seven periods to represent congestion at different times of the day. Multiclass assignments were conducted in EMME/2 to track vehicle movements by fleet; the fleets accounted for differences in vehicle age profile by county and in inspection/ maintenance program by state. Trips and VMT were then allocated from the seven assignment periods to each hour of the day using factors from Metro’s household activity survey. Separate MOBILE runs were conducted for each combination of the five fleets, two seasons, four link types, and (on freeways and arterials) 14 speed bins. Emission rates for five of the pollutants of interest were automatically produced by MOBILE 6.2, while most other toxins required the use of Additional HAPS inputs. For each pollutant whose emissions vary by speed, speed curve equations were generated in Stata to allow the calculation of emissions at any speed. All the data were exported to an Oracle database. MOBILE’s emission rate factors were applied to each link to calculate running emissions at every hour of the day. Emissions from intrazonal travel, as well as all non-running emissions, were calculated then allocated to each trip’s origin zone. Metro plans to use this link-based methodology for future air quality conformity work. The queries and programs developed for this study can also be adapted for use by other agencies with a need for geographically detailed analyses of motor vehicle emissions.

• Record URL:
  • https://onlinepubs.trb.org/onlinepubs/trispdfs/01024684.pdf
• 
• Corporate Authors:

  Transportation Research Board

  ADB50: Committee on Transportation Planning Applications
  Washington, DC  United States  20418
• Authors:
  • Stein, William R
  • Walker, Dick
• Conference:
  • Ninth TRB Conference on the Application of Transportation Planning Methods
  • Location: Baton Rouge Louisiana, United States
  • Date: 2003-4-6 to 2003-4-10
• Publication Date: 2004-3

Language

• English

Media Info

• Media Type: CD-ROM
• Features: Figures; Tables;
• Pagination: 10p
• Monograph Title: Proceedings of the Ninth TRB Conference on the Application of Transportation Planning Methods, April 6-10, 2003, Baton Rouge, Louisiana

Subject/Index Terms

• TRT Terms: Air pollution; Air quality; Algorithms; Calculation; Exhaust gases; Hazards; Highway travel; Households; Pollutants; Toxicity; Traffic assignment; Traffic congestion; Traffic volume; Travel surveys; Vehicle miles of travel
• Identifier Terms: MOBILE (Computer model); Oracle (Software)
• Uncontrolled Terms: Links
• Subject Areas: Energy; Environment; Geotechnology; Highways; Society; I15: Environment;

Filing Info

• Accession Number: 01024663
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: May 25 2006 7:57AM