Individual Streets and the City as a Whole
A neighborhood line does not necessarily divide the halachic public domain. The street can be part of a citywide network used by a much larger public.
A block belongs to a connected public network
A local street may feed major avenues, bridges, tunnels, transit centers, and business districts. Its place in that network can matter even when the traffic on one block is modest.
The public is not limited to residents living inside a proposed eruv. Workers, visitors, delivery traffic, buses, and people passing between neighborhoods use the same roads.
Neighborhood lines are not halachic walls
Cultural names, community boundaries, ZIP codes, and police precincts help people describe a city. They do not by themselves close a street or divide its public movement.
To treat a neighborhood separately, the eruv must identify a halachically effective boundary around it and address every road that passes through.
Rav Moshe's Brooklyn analysis
Rav Moshe repeatedly examines Brooklyn and New York as large connected urban realities rather than treating each neighborhood as an isolated town. His responsa consider the city population and the roads serving that population.
That approach forms important background to Crown Heights. The local route must be judged inside the Brooklyn street system, not as though the neighborhood had been moved outside the city.