The City Council shall have the right to grant unto any steam, street or interurban railway company the right for extensions, connections, branches or changes of or with the lines or tracks of any such companies on any of the streets or alleys of said city for a distance of not to exceed one mile in length, and unto any electric or motor interurban line the right to enter and operate on the streets of said city over the tracks of some other railway line, upon such terms and conditions as they may prescribe; provided, that all ordinances granting such rights shall run coexistent with the life of the franchise under which said lines or railway are operated.