CHP is located on the south side of San Juan and they love to ticket here. If you are traveling south bound, just before the Ortega Hwy overpass (just after if you are traveling north but they’re usually monitoring south because of downhill speeds) there is a split in the concrete center divider. CHP backs a cruiser between the two sides of the divider so that you are unable to see them until you have passed. They fly out into the carpool lane and get you. I’ve also seen this done with 2 cruisers – 1 in the divider to take your speed, another just south of the bend to actually pull you over. Reduce your speed at J Serra.