Section 3. Railroad corporations established in the commonwealth shall be subject to this chapter and chapter one hundred and fifty-nine which, so far as inconsistent with charters granted since March eleventh, eighteen hundred and thirty-one, shall be an alteration and amendment thereof; but this section shall not impair the validity of any special power heretofore conferred by charter or other special act upon a particular railroad corporation which had exercised such power before February first, eighteen hundred and seventy-five, or prevent the continued exercise thereof conformably, so far as may be, to this chapter and chapter one hundred and fifty-nine.