Often used when describing either a road where speeding is a poor idea, a reason for being late, or just as a story for one's peers.
"Slow down right here. There's a cop car in the corn field every mile or so for this stretch of road almost every time I pass it... see? Talk about being cop heavy."
"Sorry I'm late for poker guys. I seriously saw 12 cops on the way here. Something must be going down, or else it wouldn't be so cop heavy."
"So you'll be here in 10 minutes? Cool. Just avoid entering off Rt. 83. It was so cop heavy, there may be a drug bust or something.