Since the Shulchan Aruch uses the term shishim ribo ovrim bo it implies a thoroughfare in continuous use and not merely the presence of 600,000 people in the vicinity who would have the ability to utilize the street. Even Rav Moshe zt”l (ibid.) interpreted the criterion of shishim ribo ovrim bo to mean a thoroughfare in continuous use, such as an intercity road, which he maintained would need to have 600,000 people traversing the same section of the road (ibid., 5:28:16) on a daily basis in order for it to be classified as a reshus harabbim. Additionally Rav Moshe stated (ibid., 1:139:5, 4:87, 5:28:5, 5:29) that the criterion of shishim ribo ovrim bo when applied to a city would necessitate a population of at least 3,000,000 inhabitants (see Part 1: Shishim Ribo According to Hagaon Rav Moshe Feinstein zt”l). Only a city with such a sizable population could physically satisfy the condition of shishim ribo ovrim bo, 600,000 people collectively traversing its streets at one time. [However, Rav Moshe acknowledges that it is difficult to interpret shishim ribo ovrim bo as applying to a city (ibid., 1:139:5).]
Some claim that according to the Bais Ephraim (and other poskim as well) it’s sufficient if there is just shishim ribo in the neighborhood. This is incorrect. According to the Bais Ephraim these three conditions regarding shishim ribo must be met for the street to be classified as a reshus harabbim. The shishim ribo must: 1) Be present in the area (metzuyim shom). 2) Frequently use the street (ovrim v’shovim). 3) That they all could possibly traverse the street in one day (bechol yom). Therefore, to include neighborhoods that have nothing to do with each other is definitely not the Bais Ephraim’s shita since the shishim ribo do not frequent those streets. More so, the simple understanding of the Bais Ephraim is (Maharsham, 3:188 and Minchas Yitzchak, 8:32) that the shishim ribo would need to traverse the street itself for the street to be classified as a reshus harabbim (the only question regarding his position was whether the requirement of shishim ribo traversing the street is every day or would on most days suffice).