[Code of Federal Regulations]
[Title 40, Volume 17]
[Revised as of July 1, 2002]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR93.111]

[Page 557-558]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 93--DETERMINING CONFORMITY OF FEDERAL ACTIONS TO STATE OR FEDERAL IMPLEMENTATION PLANS--Table of Contents
 
   Subpart A--Conformity to State or Federal Implementation Plans of 
   Transportation Plans, Programs, and Projects Developed, Funded or 
       Approved Under Title 23 U.S.C. or the Federal Transit Laws
 
Sec. 93.111  Criteria and procedures: Latest emissions model.

    (a) The conformity determination must be based on the latest 
emission estimation model available. This criterion is satisfied if the 
most current version of the motor vehicle emissions model specified by 
EPA for use in the preparation or revision of implementation plans in 
that State or area is used for the conformity analysis. Where EMFAC is 
the motor vehicle emissions model used in preparing or revising the 
applicable implementation plan, new

[[Page 558]]

versions must be approved by EPA before they are used in the conformity 
analysis.
    (b) EPA will consult with DOT to establish a grace period following 
the specification of any new model.
    (1) The grace period will be no less than three months and no more 
than 24 months after notice of availability is published in the Federal 
Register.
    (2) The length of the grace period will depend on the degree of 
change in the model and the scope of re-planning likely to be necessary 
by MPOs in order to assure conformity. If the grace period will be 
longer than three months, EPA will announce the appropriate grace period 
in the Federal Register.
    (c) Transportation plan and TIP conformity analyses for which the 
emissions analysis was begun during the grace period or before the 
Federal Register notice of availability of the latest emission model may 
continue to use the previous version of the model. Conformity 
determinations for projects may also be based on the previous model if 
the analysis was begun during the grace period or before the Federal 
Register notice of availability, and if the final environmental document 
for the project is issued no more than three years after the issuance of 
the draft environmental document.