jonas,
If that *was* the reason for disqualifying an eruv in Brooklyn, then the psak can be ignored. Ocean Parkway is used by fewer than 70,000 vehicles a day, which in no way can result in the 600,000 individuals needed to disqualify an eruv. In fact, it can’t handle 600,000 even in theory, as the maximum capacity of a single highway lane is approximately 40,000 vehicles a day and that assumes no traffic lights, no backups, and peak flow for 24 hours a day.