Any such certificate of public convenience and necessity for the operation of an autobus, charter bus operation or special bus operation heretofore granted and now in effect or hereafter granted and in effect may be transferred by the holder thereof upon obtaining the approval of the Board of Public Utility Commissioners upon application to it by either the transferor or the transferee.
The transferor and the transferee shall be jointly and severally liable for any outstanding debt due the board at the time of the transfer.