No person, firm or corporation, or any employee, agent or representative of any such person, firm or corporation, shall dig a hole or make excavations in or upon any street, alley, sidewalk or curbing of the city; change, alter or destroy the surface of any such street, alley, sidewalk or curbing; obstruct the reasonable use of pedestrian travel over and upon such street, alley, sidewalk or curbing, except as provided by franchise, without first having received written permission from the City Manager, except in the case of emergencies as set out in this subchapter.