PUBLIC LAWS-CH. 32 -FEB . 20 , 1946 49 stat. 3 1- . by motor vehicle subject to part II of this Act, under agreements 49U.S.C.§§301- 327; Supp. V , §302et between such freight forwarders and common carriers (which agree- eq' ments may be required by the Commission to be subject to its approval, disapproval, or modification), in such manner as will be in furtherance of the national transportation policy declared in this Act: Provided, tatnhaul transpor- That in the case of line haul transportation between concentration points and break-bulk points in truckload lots, such terms and condi- tions shall not permit payment to common carriers by motor vehicle of compensation which is lower than would be received under rates or charges established under part II of this Act, except to the extent that such lower compensation is found by the Commission to be justified by reason of the conditions under which the services and instrumentalities of common carriers by motor vehicle are utilized by freight forwarders and the character of the services performed by common carriers by motor vehicle and by freight forwarders. "(2) The Commission, when it has prescribed such terms and condi- tions, shall by order specify a reasonable time after which subsection Infi a . (b) of this section shall no longer be effective; and the order or orders issued under this paragraph may, if the Commission deems it to be in furtherance of the national transportation policy declared in this Act, provide for the termination of the effectiveness of such subsection (b) at different times in different territories or sections. nvestigation(3) The Commission is authorized, upon complaint or upon its own initiative without complaint, to investigate and determine whether, in order to carry out the purposes of paragraph (1) of this subsection, any terms and conditions prescribed thereunder should be modified or rescinded or whether additional terms and conditions should be pre- scribed thereunder, and, after such investigation, the Commission shall by order modify or rescind any such terms and conditions, or prescribe additional terms and conditions, to the extent it finds such action necessary or appropriate to carry out the purposes of such paragraph. Hearings. "(4) No order shall be entered under this subsection except after interested parties have been afforded reasonable opportunity for hearing. Ot p erateion under "((b) Subject to the authority of the Commission to terminate b joint rates or charges. Sujet aub order the effectiveness of this su section, as provided in subsection (a) 49 Sat. 54C. 301- (2), nothing in this part or in part II of this Act shall be construed 327; Supp. V , §302 et to make it unlawful for freight forwarders subject to this part and eq. common carriers by motor vehicle subject to part II of this Act to operate under joint rates or charges. The provisions of part II of this Act shall apply with respect to such joint rates or charges and the divisions thereof, and with respect to the parties thereto, as though such joint rates or charges had been established under the provisions of such part II, and the provisions of this part shall not apply with respect thereto: Provided, however, That- Tariffs filed "(1) Joint rates or charges and concurrences contained in tariffs heretofore filed with the Commission shall become effective, without notice, as of the date of enactment of this part, unless the parties thereto file notice with the Commission, within thirty days after the date of enactment of this part, canceling such joint rates or charges and concurrences; Tariffs rejected. "(2) Joint rates or charges and concurrences, contained in tariffs heretofore offered for filing with the Commission, but rejected by the Commission, shall become effective, without notice, as of the date of enactment of this part, if filed with the Commission within thirty days after the date of enactment of this part; lJont rtes Ineect "(3) Joint rates or charges and concurrences, under which freight forwarders and common carriers by motor vehicle subject to part II 22 [60 STAT.