Conrail Infrastructure Fund Act - Amends the Regional Rail Reorganization Act of 1973 to establish a revolving fund through which proceeds from the sale of Conrail shall be used for rail-related infrastructure capital improvements. Directs the Secretary of Transportation to distribute money in the fund among the States based on the amount of State taxes exempted under the Northeast Rail Services Act of 1981. Requires that the remainder of such funds be allocated on the basis of a formula relating to Conrail mileage on April 1, 1976.