This would be a reallly cool application if PIR's were capable of counting "horde" foot traffic, like a giant mass of people streaming out of a door during an a

This would be a reallly cool application if PIR's were capable of counting "horde" foot traffic, like a giant mass of people streaming out of a door during an alarm. I don't think that something like a PIR could handle that number of people, since it's just the single beam.