With porch minyanim active in Crown Heights, some have erected eruvs between porches that extend onto the sidewalk. However, rabbonim say that it should not be used.
Harav Yosef Braun via Ask the Rav
This Shabbos an Eruv was constructed by a few of my neighbors. The Eruv was constructed in front of a number of houses, and included the sidewalk in front of these houses. It was built, in order to make it easier for people to carry their Siddurim, to participate in a porch Minyan on their block.
I know the Rabbonim have prohibited using an Eruv in our community, for various reasons. Is a sidewalk Eruv also problematic?
Although it was created for current use, it’s probable the Eruv will stay up indefinitely.
Can I use this Eruv?
Harav Braun responds:
The Beis Din does not approve of such an Eruv unless it would have an actual fence with doors.
Additionally, making an Eruv on a public sidewalk is not allowed since the area belongs to the city.