March 10-13, 2002. Just south of the intersection of Rt 7 with I-45 mear Centerville, a DPS trooper parks with radar & laser off. To sounthbound traffic he is a surprise around the curve, to northbound traffic he is a surprise coming over a hill. He then radios other cars north and south, who come in from behind the speeders, waits for them to speed up again, and radars them for the ticket. The stalking aspet is what makes this trap radar-detector proof; my actual ticket was 30 miles away from the spotter car. Before seeing the spotter car, the only radar & laser emissions were low strength and from the rear; during the stalking phase there were no measureable emissions.