"LAPD can only enforce speed limits with radar on just 28 percent of the streets in Los Angeles that require traffic studies"

LAi:

In order for the LAPD to enforce speed limits on surface streets throughout the city using radar, those streets must have been subjected a traffic speed survey conducted by the Los Angeles Department of Transportation (LADOT) within the past seven (to ten) years.

The problem for the city and its police department, says a new report from LADOT, is that the lion's share of speed surveys in L.A. are obsolete.

...

LAPD issued 99,000 speeding tickets in 2010, according to Streetsblog Los Angeles. That number dropped to just 16,000 in 2015. While LAPD can still enforce speed limits, they can only do so on those roads by pacing cars from behind. Pacing can be dangerous, and the preferred method of speed enforcement is with radar or lasers.