The bollards in Times Square greet pedestrians who pass through busy car-free plazas.

In May, they likely saved lives, after a driver on drugs plowed his car into people in the location, killing a young woman. The car ultimately crashed into the metal poles.

There were no bollards, however, along the Hudson River Park bike path when an alleged terrorist drove a truck down it on Halloween, killing eight people.

"When someone in a vehicle plows into a group of innocent pedestrians, it's disgusting," Mayor Bill de Blasio said at a press conference Tuesday morning. "But we know there are some out there who mean to do us evil, and we will protect against it."

The mayor said the city will begin installing 1,500 new metal bollards around New York at a cost of $50 million. Some will replace temporary concrete barriers that have been placed around the city to stop cars, but officials refused to say where the other bollards would go.

"We're not going to get into the specifics of exactly where they are going to be," City Transportation Commissioner Polly Trottenberg said. "I think you can see some of the iconic places around the city, where we have those temporary concrete blocks — those will be some of the places and we will be looking for new places, too."

The Times Square announcement was de Blasio's first official event since his inauguration. He took no questions, but he did appear with Manhattan City Councilman Corey Johnson, who is poised to be elected the next city council speaker by his colleagues Wednesday.

"I think tomorrow will be a very important day for the council member and for the whole city," de Blasio said. "So I welcome him and I warmly congratulate him in advance: Council member Corey Johnson."

The mayor did not lobby for Johnson to get the job, the way he did four years ago for former Speaker Melissa Mark-Viverito. But de Blasio seemed to try to start off the new relationship on friendly footing.

"I stand here fully supporting the installation of security bollards throughout all five boroughs," Johnson said at the press conference.

The city will begin installing the new bollards in March, but it may take a few years before all 1,500 are in-place.