Angry bus drivers slowed traffic to a crawl in upper Manhattan and The Bronx on Tuesday morning to protest a law passed under Mayor Bill de Blasio’s Vision Zero.

Drivers would not enter crosswalks unless they were clear of any pedestrians, and came to a complete stop if there were people crossing between 7 and 9 a.m.

A new law created under Vision Zero, the city’s plan to end all traffic deaths, criminalizes drivers if they seriously injure or kill pedestrians who are in a crosswalk.

Union officials handed drivers a cartoonish image of de Blasio arresting a female driver in front of a bus which instructed them not to turn if the intersection was not clear.

“The point of today’s outreach is to educate and instruct drivers how to operate under the de Blasio administration’s Right of Way,” said John Samuelsen, who heads their union, TWU Local 100. “They should not move their buses until the crosswalk is completely free of pedestrians.”

Seven bus routes were involved between The Bronx and Washington Heights on lines that included the Bx5, Bx35 and Bx36. Traffic was backed up on Wadsworth Avenue to White Plains Road and Lafayette Avenue.

Sara Reid, 41, of The Bronx said she had been sitting on the Bx13 for 35 minutes.

“This is horrible,” she said. “Now everyone on this bus is late because they want to protest.”

An MTA spokesman said bus drivers are already trained and instructed to stop for pedestrians at crosswalks.

“If it’s the TWU’s idea to garner additional support against Vision Zero by deliberately impacting and delaying the commute of thousands of our bus customers, they are certainly going about it the wrong way,” spokesman Kevin Ortiz said.

The action targeted routes in the Inwood district of Councilman Ydanis Rodriguez, who heads the City Council transportation committee.

It also slowed down service in Councilman Richie Torres’ district in The Bronx.

Union officials said they were selected because the council members have not supported legislation that would prevent bus drivers from being arrested in a collision where there is no evidence of recklessness.

The union has also said the buses have blind spots because of large side-view mirrors, and that the city’s signal system gives drivers making a left turn and pedestrians a green light at the same time.