Quotation for Bava Batra 2:14
אִילָן שֶׁהוּא נוֹטֶה לִרְשׁוּת הָרַבִּים, קוֹצֵץ, כְּדֵי שֶׁיְּהֵא גָמָל עוֹבֵר וְרוֹכְבוֹ. רַבִּי יְהוּדָה אוֹמֵר, גָּמָל טָעוּן פִּשְׁתָּן אוֹ חֲבִילֵי זְמוֹרוֹת. רַבִּי שִׁמְעוֹן אוֹמֵר, כָּל הָאִילָן כְּנֶגֶד הַמִּשְׁקֹלֶת, מִפְּנֵי הַטֻּמְאָה:
If a tree projects into the public domain, it is cut [i.e., its lower branches are cut] so that a camel and its rider may pass. R. Yehudah says: A camel laden with flax or with bundles of vine rods. [And it is not necessary to cut for a camel and its rider, for the rider can bend down and pass under it.] R. Shimon says: Every tree (is to be cut) against a plummet against uncleanliness [i.e., lest the branches "tent" over an olive-size of a dead body or the like and render unclean one passing beneath them. The halachah is in accordance with the first tanna alone.]
Jerusalem Talmud Bava Batra
If a tree overhangs the public domain, one has to cut it so that a camel with a rider on it may pass; Rebbi Jehudah says, loaded with flax or bundles of vine cuttings109They are very light and take up a large volume.. Rebbi Simeon says, any tree [must be cut] along the plumb line because of impurity105,The owner of the field may cut these trees vertically at his property line.110R. Simeon essentially rejects the rabbis’ rule as following Gentile law (Corpus iuris, Decretum de arboribus caedendis requires that branches overhanging a public road must be cut up to a height of 15 Roman pedes, not quite 4.5 m.) He insists on a Jewish rationale. The impurity of the dead is transferred not only by touch but by being under one “tent” with a corpse. The crown of a tree forms such a “tent.” If the tree overhangs a road but grows inside a fence or wall which obstructs the view, a person passing under it could be inadvertentently become severely impure (cf. Nazir 7:3, Notes 163–164). Therefore, in the Land of Israel all overhangs have to be eliminated. He has no rules for other countries..