Elevated Train Tracks As An Eruv
‘Pi Tikra Reaches’
Approximately 50 years ago, Rabbi Moshe Feinstein, zt”l, (Igros Moshe, Orach Chayim 1:138) was asked his opinion on creating an eruv in Brooklyn. Rabbi Rafael Ber Weismandel, zt”l, had proposed that an eruv could be made in Brooklyn because it’s surrounded on three sides by man-made walls that hug the ocean and river, and the fourth side is closed off by elevated train tracks.
According to the sugya of pi tikra, the edge of a roof can be considered like a wall, which descends to close off a reshus hayachid. Rabbi Weismandel ruled that the train tracks formed such a roof.
Rabbi Feinstein responded with a lengthy teshuvah in which he rejected the proposal. One of his arguments is based on our sugya, in which we find a machlokes over when the halacha L’Moshe M’Sinai of pi tikra applies. According to the opinion accepted by the Rema (Orach Chayim 361:2), pi tikra applies only if there are already two solid walls with a common corner that form an “L” shape. Pi tikra can then form a third wall.
However, if the two solid walls are parallel, such that people can freely pass between them, they negate the wall of the pi tikra. In the case of the elevated train, there is nothing to stop people from passing freely beneath the tracks. Therefore, the halacha L’Moshe M’Sinai of pi tikra doesn’t apply.
Only Beneath The Tracks
Furthermore, argues Rabbi Feinstein, pi tikra is only relevant to the area beneath the roof. Pi tikra allows us to make an imaginary wall to enclose the area beneath it. So, in Brooklyn, the area beneath the tracks may very well be a reshus hayachid. However, the pi tikra of the tracks does not enclose the area beyond the tracks – i.e., the rest of Brooklyn.
We find this argument presented in our sugya by Rava, who claims that if a sukkah is built next to a canopy, we cannot apply pi tikra to the edge of the canopy to form a wall for the sukkah. Pi tikra can only form a wall for the area beneath the canopy.
For these and other reasons, Rabbi Feinstein concluded that an eruv cannot be constructed in Brooklyn.
Bypassing A Municipal Directive
Yet, numerous authorities nowadays support and establish eruvin in Brooklyn and similar localities. Many take their cue from an interesting eruv ruling of the Chazon Ish (Orach Chayim 79:1). In a certain city, the government didn’t permit Jews to build a tzuros hapesach over the main street and, since the street was wider than 10 amos, a lechi or kora would have been ineffective.
The Jews therefore built a balcony extending over part of the street, so that the area from the end of the balcony until the opposite side measured less than 10 amos. The edge of the balcony was considered to be a pi tikra forming an imaginary wall, which diminished the width of the street. The remaining amount was less than 10 amos, and a lechi was then sufficient to permit carrying.
Apparently, the Chazon Ish considered the pi tikra of the balcony to be a valid mechitza, even in regard to the street beyond the balcony – and even though people passed freely underneath.