Enforcement of two of drivers' most dangerous behaviors—speeding and failure to yield—has increased dramatically in the six months since Mayor de Blasio introduced his Vision Zero initiative. But while the number of summonses issued has ballooned dramatically in some precincts, it has stagnated and even slowed in others.

The enforcement analysis comes from a newly released study from the advocacy group Transportation Alternatives.

Overall, the study shows that summonses for speeding have increased 32 percent over the past six months compared to last year, while failure to yield summonses have skyrocketed by 153 percent.

But transit advocates are troubled by serious inconsistencies, particularly in adjacent precincts—while the officers in one precinct may be ticketing diligently, their efforts are somewhat in vain when officers in the adjoining precinct fail to match their vigilance, despite similarities in street designs and traffic conditions.

The study cites Harlem's 26th precinct, which nearly doubled the number of speeding summonses issued from the same time last year, while the neighboring 30th precinct in Washington Heights cut its speeding summonses in half.

"This inconsistency is enough to undermine positive enforcement efforts. Varying levels of enforcement reinforce the mentality that drivers can 'get away with it,'" the report states. "Every violation that goes unenforced is implicit encouragement for drivers to commit the violation again."

To smooth over these gaps, the report offers a few recommendations, including the creation of an executive officer for each borough command to oversee enforcement, educating officers on the importance of Vision Zero and placing additional emphasis on the most deadly violations.

Earlier this year, the NYPD's Transportation Chief Thomas Chan briefed council members on his plan for increased enforcement, which included targeting speeding and failure to yield at the precinct level, as well as conducting intensive investigations for all collisions resulting in critical injury.

Chan said additional officers were also slated to be trained to use speed guns, of which the NYPD was set to acquire an additional 200, as well as increase Highway Division patrols from 210 to 270.

Read the full report below:

Report-Card-Six Months of Vision Zero Traffic Enforcement