Walls, Gates, and Former Toll Barriers in Manhattan
Manhattan proposals relied in part on substantial built structures and former barriers at crossings. Their status depends on whether they form the gates or walls required by the governing psak.
Substantial structures around the island
Manhattan proposals pointed to seawalls, retaining walls, bridge structures, railings, and other substantial construction. Each feature had to reach the required height, follow a usable line, and join the next part of the enclosure.
A massive structure can still fail as a halachic wall if it is interrupted by access, slopes away in the wrong form, or never connects to the claimed route.
Toll barriers and bridge gates
Earlier bridge and tunnel approaches included toll barriers and gates. Whether they functioned as delasos depended on their position, their ability to close the relevant opening, and the psak governing actual closure.
A traffic arm across several lanes may leave sidewalks, service lanes, or the broader breach open. Its ordinary use for collecting tolls does not itself make it a halachic door.
The physical city changes
Toll systems, gates, ramps, and shoreline construction can be removed or rebuilt. A route dependent on those structures must be dated and inspected in the period for which permission is claimed.
This is one reason an older Manhattan proposal cannot be invoked from memory. The present perimeter may no longer contain the walls or barriers on which the original analysis relied.