The city's "Vision Zero" plan for pedestrian safety is coming into focus this week: after a year of crash data analysis and community outreach, the city has mapped out a constellation of unsafe intersections, or "priority" locations, where the majority of crashes occur in each borough.

Queens was the first borough to receive its Vision Zero plan Monday, which targeted engineering, planning and enforcement on two top traffic ills: speeding and "Failure to Yield" — when turning vehicles don't stop for pedestrians who have a walk signal.

But a Twitter war over the weekend between the Transport Workers Union and pedestrian advocates cast doubt on the right way to enforce Vision Zero.

After a bus driver was arrested and charged with "Failure to Yield" in Williamsburg on Friday, the union said the city is treating its bus drivers like criminals. The driver struck a teenage girl in a crosswalk, causing serious injury. In a statement, the union said bus drivers should be exempt from city code Section 19-190, passed in August, that criminalizes "Failure to Yield."

But Department of Transportation Commissioner Polly Trottenberg said Vision Zero applies to all drivers. "We really don't want Vision Zero to be a war on bus drivers," she said. "That is not the intention." She said the city is working with MTA and the Transport Workers Union to reduce fatalities and doesn't want this to be an "adversarial" process.

The city police department's Chief of Transportation Thomas Chan said arrest situations are taken on a case-by-case basis by police. Last year, he said, speeding enforcement increased by 48 percent, and failure to yield enforcement increased by 145 percent. "We definitely think that had an impact," Chan said. "The drivers are more aware... that they should slow down and yield to the pedestrians."

The Queens plan calls for increased enforcement at priority locations. 3,000 new speed limit signs will be posted in 47 priority areas this year. The plan also calls for changes in traffic light timing to rein in speeders trying to beat the reds and expands "exclusive pedestrian crossing times" at 72 priority intersections by the end of 2017.

The other four borough plans will release this week on the Department of Transit's website.