ISTEA Integrity Restoration Act

ISTEA Integrity Restoration Act - Authorizes appropriations out of the Highway Trust Fund (other than the Mass Transit Account) for the: (1) National Highway System (NHS); (2) Surface Transportation Program (STP); and (3) Federal Lands Highway Program, including Indian reservation roads, public lands highways, and parkways and park highways.

(Sec. 4) Defines "highway funds" as funds apportioned and allocations authorized under this Act for the fiscal year and funds allocated to a State for the preceding fiscal year for Federal-aid highways and highway safety construction. Revises the apportionment of NHS funds to allocate 0.4 percent (previously, one percent) to U.S. territories and possessions, and the remaining 99.6 among the States according to a formula based on population density. Includes bridge construction and related activities among eligible NHS projects.

(Sec. 5) Repeals provisions regarding: (1) apportionments for resurfacing, restoring, rehabilitating, and reconstructing the Interstate System (IS); and (2) the transfer of interstate construction apportionments, the transfer of funds for STP projects, and limits on new capacity.

(Sec. 6) Includes bridge construction and related activities as an eligible activity within the streamlined STP. Makes eligible under the STP an area of a State that is a nonattainment area for ozone or carbon monoxide, or for particulate matter with an aerodynamic diameter smaller than or equal to ten micrometers resulting from transportation activities, or for any combination thereof, for congestion mitigation and air quality improvement projects without regard to any Department of Transportation limitation relating to the type of ambient air quality standard addressed by such project. Revises: (1) State certification procedures; and (2) procedures for payments to States for eligible STP activities.

(Sec. 7) Directs that, for purposes of STP and IS provisions, population shall be determined based on the most recent estimate prepared by the Secretary of Commerce.

(Sec. 8) Repeals provisions regarding: (1) the highway bridge replacement and rehabilitation program; and (2) the congestion mitigation and air quality improvement program.

(Sec. 10) Replaces provisions regarding minimum allocations to States with an apportionment adjustment program under which the Secretary shall apportion among the States amounts sufficient to ensure that the ratio of the highway funds of a State to highway funds of all States for the fiscal year is not less than the adjustment percentage specified for that State under this Act. Requires each State to receive additional apportionments so that its percentage of highway funds is not less than 95 percent of the percentage of estimated tax payments attributable to highway users in the State paid into the Highway Trust Fund. Repeals: (1) existing apportionment adjustment programs; and (2) set-asides for interstate discretionary projects.

(Sec. 12) Reduces from 3.75 to 2.35 the percentage of program funds authorized to be set aside for administrative costs.

(Sec. 13) Sets forth provisions regarding permissible transfers of unobligated balances of funds apportioned to a State for: (1) congestion mitigation and air quality improvement; (2) interstate construction and maintenance; (3) bridge replacement and rehabilitation; and (4) the STP.