738. Carrying in an Alley

Shabbos 17:6

Let’s say that an open alley (i.e., with two walls) ends in the middle of a yard that belongs to many people. If the alley is not opposite the entrance to the yard, it is considered closed and nothing further is required at the side of the yard. If it ends at the side of the yard, one may not carry in the alley. If the yard belongs to one person, it is prohibited to carry in the alley even if it leads to the middle of the yard. This is because a property owner sometimes builds on the side of a yard. If he does so, the end result may be that the alley ends up at the side of the yard.

Shabbos 17:7                                                             

One may carry in an alley based on a pole or a beam only when: a number of houses and/or courtyards open into the alley; the alley is four cubits or longer (6 feet plus); and the length of the alley exceeds its width. If the length and the width of an alley are the same, it is considered a courtyard and one may only carry within it after erecting two poles with no minimum measure as to their width, one on each side. One may also erect a board four handbreadths wide (about a foot) on one side.