Except on streets which may be designated by the Mayor
and roped off or protected by signs, it shall be unlawful for any
person to coast, slide or ride with or on any sled or sleigh or to
cause or permit any vehicle, by whatever name called, other than motor
vehicles, wagons, carts, bicycles or other similar vehicles, to roll
on or run by gravitation along, over or upon any sidewalk, street,
alley or highway within the City.