States that whenever the Interstate Commerce Commission determines that the requirements of the Interstate Commerce Act should not be applied to any person or class of persons or to any services or transportation because such requirements are not necessary to effectuate the National Transportation Policy declared in such Act or to effective regulation by the Commission thereunder, and would serve little or no useful public purpose, it shall exempt such persons from regulation under this Act for such period of time as may be specified. Provides that such exemption may be revoked whenever the Commission finds that the exempted services are necessary to transportation policy and would serve a useful public purpose.