Rav Moshe zt”l stated (Igros Moshe, O.C. 5:28:5) regarding Brooklyn’s mechitzos, “Until now they [the mechitzos] did not exist but that one can investigate” (see also ibid., Addendum to O.C. 4:89).
These are the facts:
That there are three mechitzos nowadays enclosing more than 95 percent of the Brooklyn waterfront, is obvious even to the most casual of observers (see Part 3: Why Brooklyn Is Not a Reshus HaRabbim). Therefore, according to Rav Moshe, Brooklyn is classified as a reshus hayachid and an eruv of tzuras hapesachim can be erected.
These mechitzos were evaluated by the following rabbanim to see whether they fulfilled Rav Moshe requirements:
Members of Rav Yechezkel Roth shlita’s Bais Din; see Emek HaTeshuvah (5:19) and Appendix 8.
Rav Shlomo Gross shlita, Belzer Dayan of Boro Park.
Rav Tuvia Goldstein zt”l sent a select group from his kollel Emek Halacha.