U.S. Environmental Protection Agency
Office of Mobile Sources
August 24,1999


Document Released for Stakeholder Review and Comment

Facility-Specific Speed Correction Factors
Report Number EPA420-P-99-002

The Office of Mobile Sources, Assessment and Modeling Division
announces the release of "Facility-Specific Speed Correction
Factors" for stakeholder review and comment.  This document
EPA420-P-99-002 (also known as M6.SPD.002.)is available at the
MOBILE6 section of the OMS Web Site
(http://www.epa.gov/oms/m6.htm)

Although the adjustments described in this document are called
"speed" correction factors, the adjustments include all of the
effects on emissions caused by differences in driving behavior,
of which average speed is the most obvious and easiest to
measure.  The speed correction factors described in this document
are proposed to be used in MOBILE6 to replace the speed
correction factors now used in MOBILE5 for all light duty
passenger cars and light duty trucks of all model years and
technologies.  The speed correction factors for heavy duty
vehicles, diesel fueled vehicles and motorcycles from MOBILE5
would be retained for use in MOBILE6.  This document also
proposes a method for applying the new speed correction factors
to future technology vehicles for which no data is yet available.

The new MOBILE6 speed correction factors specifically account for
aggressive driving behavior not represented in older driving
cycles.  They also allow for evaluation of vehicle emissions by
roadway type (facility) and by roadway segments (links).  There
are four roadway types modeled in MOBILE6:

                    Freeways
                    Arterial/Collectors
                    Freeway Ramps
                    Local Roadways

Comments on this report and its proposed use in MOBILE6 should be
sent to the attention of Dave Brzezinski.  Comments may be
submitted electronically to mobile@epa.gov or by fax to (734)
214-4939 or by mail to MOBILE6 Review Comments, USEPA Assessment
and Modeling Division, 2000 Traverwood Drive, Ann Arbor, MI
48105. Electronic submission of comments is preferred.

In your comments, please note clearly the document that you are
commenting on including the report title, and the code number
listed.  Please be sure to include your name, address,
affiliation, and any other pertinent information.

This document is being released and posted on August 24, 1999.
Comments will be accepted until sixty (60) days after date of
posting.  EPA will then review and provide a summary of those
comments and how we are responding to them.

Thank you for your continuing interest in the development of
MOBILE6.
                                 
Sincerely,

Emission Inventory Group, Assessment and Modeling
Division US EPA Office of Mobile Sources