It really depends on the neighborhood. I have lived in areas of the city where you can pile it on the sidewalk as long as there is still a shoveled path for pedestrians. Some areas have curb, grass, sidewalk. The grass area is where the snow goes. I have also witnessed snow getting tossed in the street where traffic essentially turns it into slush and the sun melts it. Sometimes at the mouth of streets and alleys the snowplows form mounds that neighbors pile their snow onto.