The facilities for travel and business on either of the roads of any corporations acting under the provisions of § 39-6-16 — § 39-6-18 shall not be diminished by the terms or conditions of any agreement under this chapter, and copies of all contracts made under the provisions of the sections shall be filed with the division of public utilities and carriers within thirty (30) days after execution thereof, which shall set forth a full statement thereof in its next annual report.