A bill to amend title 23, United States Code, to provide more flexibility in allocation of interstate substitute funds.

Revises the substitution guidelines under the Federal Aid Highway Program to provide that when the Secretary of Transportation has withdrawn approval of an Interstate route (or portion thereof) upon the joint request of a State Governor and local officials, the Federal share of the cost to complete such withdrawn route shall be available for specified substitute projects selected by local officials of the area from which the route was withdrawn.

Establishes guidelines under which the Secretary is authorized to approve Interstate route withdrawals and substitute projects after September 30, 1983, in certain circumstances, but not later than September 30, 1986.

Directs the Secretary to use the Federal share of certain adjusted cost estimates in making apportionments for substitute highway projects on October 1 of the year of adjustment if the Congress has not approved the appropriate cost estimate to make such apportionment.