4.—Where a service of trains on any railway line was temporarily discontinued under the Emergency Powers (Córas Iompair Éireann) (Reduction of Railway Services) Order, 1944 (S. R. & O., No. 354 of 1944), and no determination in relation to the line has been made by the Transport Tribunal before the passing of this Act under section 55 of the Transport Act, 1950 (No. 12 of 1950), Córas Iompair Éireann shall not be under an obligation to restore the service before—

(a) the determination by the Transport Tribunal of an application for an exemption order in relation to the line under that section made not later than three years after the passing of this Act or within such additional period, not exceeding two years, as the Minister may by order provide, or

(b) if no such application is made, the expiry of that period or additional period.