The Commission shall investigate the cause of any accident on any railroad which, in its judgment, requires investigation. The Commission shall require every common carrier by railroad doing business in this Commonwealth to file all reports required by the Federal Railroad Administration pursuant to the Federal Accidents Reports Act and regulations issued pursuant thereto to the Commission at its office in Richmond, Virginia, provided that neither such report nor any part thereof shall be admitted as evidence in any suit or action for damages growing out of any matter mentioned in such report.