Some 1,500 barriers are to be installed in New York City in order to prevent cars hitting pedestrians.
The protective measures are to be introduced after several deadly incidents in the city, and will cost $50 million (£36,700).
The city’s mayor, Bill de Blasio, said the protection would be put in place in key locations such as Times Square.
"In 2017, New Yorkers witnessed the horrible capacity of people willing to do us harm, whether it was in our subways, on our bike paths or in Times Square," Mr de Blasio said.
"We know we have to do even more to keep people safe and that's why we conducted a review on how best to secure our streets and public spaces, and we formulated a plan of action."
In May, a man said by police to be high on drugs drove through crowds for more than three blocks, killing an 18-year-old tourist from Michigan. The vehicle was eventually stopped by one of the squat metal barriers.
Temporary concrete blocks were put up along the Seventh Avenue pavement while city officials weighed a long-term solution and considered banning vehicle traffic from the area altogether.
Then, on Halloween, an Islamic State-inspired attacker drove down a busy bicycle path near the World Trade Centre, authorities said. He killed eight people before he wrecked his rented truck and was shot by police.
Barriers were also placed there to keep cars out of the bike path.
The rollout will begin in March. Meanwhile, the temporary blocks already set up will remain in place.