An NYPD anti-crime initiative on trouble-prone Bronx and Queens subway lines resulted in a 20 percent reduction in major felonies — and now it will be expanded citywide.

The program is also being expanded. At first, it served only weekends, but now it will include weeknights, said NYPD Transit Chief Joseph Fox.

Uniformed cops rode trains with a history of high crime from the first station to the last, and conductors announced their presence to riders.

The 20 percent drop in major felonies from July 16 includes a 37 percent decrease in robberies, a crime that has been on the rise due to the theft of pricy smartphones and iPads.

“This reduction is compared to the same period in 2011 during the days and hours that these officers are working,” Fox said.

He added that the NYPD will add 100 more cops to the plan.