“That was necessary to immediately secure those areas in light of these new trends we’ve seen,” Mr. de Blasio said. “But we knew we needed long-term solutions, we needed permanent barriers.” Bollards, city officials said, will allow pedestrians to move more freely than the concrete barriers, which take up more room and are more cumbersome to navigate in a crowd. “People have to be able to get around, but they have to be safe at the same time,” the mayor said.
Aside from Times Square, city officials declined to say where many of the bollards would go and noted that it would take a few years to install all 1,500 of them.
In a 2010 article in its magazine, Inspire, Al Qaeda encouraged adherents to use vehicles “to mow down the enemies of Allah.” But the tactic did not really catch on among would-be terrorists until several years later, when the Islamic State began to call publicly for vehicle attacks. Since then, counterterrorism officials in New York City have watched with concern as men in cars and trucks rammed pedestrians in a string of deadly attacks from Quebec to Nice to Berlin.
The spate of vehicle attacks prompted discussion about what more the city could do to insulate pedestrian areas from traffic, and whether, in Times Square at least, it made sense to further reduce traffic along some blocks.
At the news conference, the mayor did not take questions and said little regarding tactics, besides installing the bollards.
Bollards are not new to Times Square. They were installed by the dozens in the area in 2016.
Last May, bollards on 45th Street eventually stopped the car whose driver, high on PCP, had driven along three city blocks of sidewalk, killing an 18-year-old woman and injuring 20 people.
The city’s transportation commissioner, Polly Trottenberg, said that installing bollards is complicated because of the infrastructure and subway lines below some of the city’s busiest areas. “If you want to make them so they can really stop a vehicle, they need to go some distance into the ground,” Ms. Trottenberg said.
A spokesman for the Transportation Department, Scott Gastel, said that there are “nearly 50 locations with such permanent bollards” around the city, but that they had mainly been installed by private entities, or diplomatic missions.