flag_direction {N,E,W,S}
set flag_direction by the direction of 3 connected sensor door.
kick out all sensor record on reverse direction.

Intersection_Start, Intersection_End.
record intersection_Start by first sensor(direction doesn’t matter)
record intersection_Start by last sensor(direction doesn’t matter)
kick out all sensor record not between intersections and not in sequence.

kick out sensor data of same car within 20 minutes.