Coming into Calhan from the South, the Calhan Hwy speed limit quickly drops from 55 mph to 25 mph, just as the street name suddenly changes from Calhan Hwy to Yoder St. This is on the east side of town, just before highway 24.

I do not know where the cop hides, but he is clocking individuals both on highway 24 heading east/west, but also has a view of Calhan Hwy S where the speed limit suddenly changes. Thus it is a dual speed trap.