Around 6:15 a.m. on a recent Thursday, Rabbi Moshe Tauber parked his van in the merge lane of the Henry Hudson Parkway at 72nd Street. He turned on his hazard lights and ran out of the vehicle with a flashlight. His wife, Chaya, sitting in the passenger seat, watched anxiously.Tauber, 51, turned his head upward, shone his flashlight on the nylon fishing wire strung up 30 feet from the ground between two poles, and ran back to the car. All clear — the boundary was unbroken.For the past 25 years,