The permittee shall maintain safe crossing for two lanes of vehicle traffic at all street intersections where possible, and safe crossing for pedestrians at intervals of not more than 300 feet. If any excavation is made across any public street, alley or sidewalk, adequate crossing shall be maintained for vehicles and pedestrians. If the street is not wide enough to hold the excavated material without using part of the adjacent sidewalk, a passageway at least one-half of the sidewalk width shall be maintained in and along such sidewalk line. (Ord. 119 § 1(1012), 1969).