A bill to amend the Clean Air Act to incorporate certain provisions of the transportation conformity regulations, as in effect on March 1, 1999.

Amends the Clean Air Act to permit the implementation of transportation projects that received certain approval even if the Administrator of the Environmental Protection Agency subsequently determines that the conformity of the applicable transportation plan and program to the implementation plan for national air quality standards has lapsed. Describes such approval as approval of plans, specifications, and estimates under Federal highway provisions, certain full funding grant agreements under Federal mass transportation provisions, or equivalent approvals or authorizations. Permits projects that received such approval before March 2, 1999, to be implemented without any additional conformity determination.

Authorizes transportation projects for which a review under the National Environmental Policy Act of 1969 (NEPA) has been completed within the two-year period preceding a conformity lapse to be implemented for a period ending not later than one year after the date the lapse commenced.

Directs the Administrator to promulgate criteria and procedures for demonstrating and ensuring conformity in the case of transportation plans, programs, and projects. Requires regulations in effect before March 2, 1999, to be in effect as originally promulgated beginning on this Act's enactment and ending on the earlier of the effective date of regulations promulgated under this Act or one year after this Act's enactment. Applies the earlier regulations to any conformity lapse that occurs before the effective date of subsequent regulations but only until the date of promulgation of such regulations.

Provides that in the case of a project for which a review under NEPA has been completed, non-Federal funds applied toward right-of-way acquisition or design activities during a period of conformity lapse may be attributed to a State's obligated share of project funding under Federal highway or transportation provisions at such time as a transportation plan or improvement program that includes the project is determined to conform to the implementation plan. Makes certain prohibitions on approval, acceptance, or funding under conformity provisions inapplicable to the funding of any mass transportation project.

(Sec. 2) Provides that an area shall not be considered to be out of conformity with an implementation plan for the sole reason that the area is a nonattainment area with respect to an ozone air quality standard promulgated after January 1, 1997, until one year after the date on which the Administrator determines that motor vehicle emissions estimates and reductions contained in an implementation plan (regardless of whether the plan has been approved) are adequate.