Sec. 15.6  Further regulatory powers.
   The grant of every franchise shall be subject to the right of the city[,] whether in terms reserved to not, to make all regulations which shall be necessary to secure in the most ample manner the safety, welfare and accommodation of the public, and the right to make and enforce all such regulations as shall be reasonably necessary to secure adequate, sufficient and proper service, extensions and accommodations for the people and insure their comfort and convenience.  Such fight of the city shall include but shall not be limited to the following, viz:
   (a)   To repeal the same for misuse, or nonuse, or for failure to comply with the provisions thereof;
   (b)   To require continuous and interrupted service to the public in accordance with the terms of the franchise throughout the entire period thereof;
   (c)   To require the public utility to which any franchise is granted to permit joining use of its property and appurtenances located in the streets, alleys, and public places of the city, by the city and other utilities, insofaras such joint use may be reasonably practicable and upon payment of reasonably rental therefor; provided that, in event of the inability of the parties to agree, upon application by either party, the council shall provide for arbitration of the terms and conditions of such joint use and the compensation to be paid therefor;
   (d)   To pay such part of the cost of improvement or maintenance of the streets, alleys, bridges, and public places of the city as shall arise from its use thereof[,] and to protect and save the city harmless from all damages arising from said use.