How a Valid Eruv Changes the Practical Status of Carrying
A valid eruv does not permit hotza'ah everywhere. It creates and joins a defined enclosed area in which carrying can be permitted under the required conditions.
The physical enclosure
Walls, fences, natural boundaries, or valid forms of doorways must surround the area as halacha requires. Every opening and transition along the route has to be accounted for; a mostly complete line is not automatically a complete enclosure.
If the place is a reshus harabim, an ordinary tzuras hapesach may not be enough. The status of the streets must therefore be settled before the technical route of poles and wires can be evaluated.
The communal joining
Eruv chatzeiros or shitufei mevo'os joins residents for carrying within the enclosed area. A designated food is transferred on behalf of the residents through a valid act of zikui, and sechiras reshus may also be required where property is held by people who do not participate in the eruv.
These arrangements do not repair a missing wall or invalid street enclosure. Conversely, a sound boundary does not replace the communal joining required by Chazal.
Continuing validity
The enclosure must remain valid on the Shabbos when it is used. Construction, weather, tree work, utility repairs, a sagging wire, or a moved pole can change a route that was valid the week before.
Inspection and repair protect a valid eruv, but they cannot create validity that was never established. The original halachic basis, continuing supervision, and physical maintenance each answer a different question.
The practical position in Crown Heights
The Crown Heights Rabbonim have not accepted the publicized boundary as a valid eruv for the neighborhood. Weekly inspection of that route therefore does not change the local psak or permit carrying.
The practical question is not whether some pieces of the route resemble parts of other eruvin. The complete enclosure and all of its legal requirements must be accepted as valid for this place.