Lounge in Them. Dash Through Them. But Don’t Call Them Parks.

NEW YORK — A decade ago, when Dr. Pezhman Hourizadeh opened his optometry practice in Corona, Queens, his storefront faced a street that was only a block long and mainly served as a parking lot for vans from nearby moving companies. “Patients who came by in cars couldn’t come in,” he recalled.

The streetscape is different now. There is no street.

The city closed it as the first step in creating a plaza, a $5.4 million project that changed the look and feel of the block. Nowadays, the view from Hourizadeh’s waiting area is of people sitting at tables shaded by orange umbrellas.

What happened in Corona is urban alchemy — turning a short stretch of asphalt into a little oasis. It is alchemy that the city has performed over and over in the last 10 years, radically transforming some of the busiest corridors in New York City. The plaza outside Hourizadeh’s shop is the newest of 74 pedestrian plazas — slivers and slices here and there meant to reduce traffic congestion and pollution.

They add up to 30 acres of land that used to be streets. That is the equivalent of almost 23 football fields, a modest-sounding total that nonetheless has proved meaningful — and controversial.

“In the grand scheme of things, not a lot of space has been given over to pedestrian plazas,” said Paul Steely White, the executive director of Transportation Alternatives, an advocacy group, “but it’s important space. It’s high-demand space. It’s in the city’s densest neighborhoods. It’s at crossroads. It’s in key commercial centers. The impact of reclaiming that 30 acres has been enormous.”

Also, he said, in a traffic-choked city, closing streets, rerouting drivers and building plazas sends a message: “Driving culture is not the predominant street culture.”

To people who crisscross them — strolling, perhaps, or dashing to appointments they are late for — the plazas look like public parks on the street, but they are different from parks. On the city’s organization chart, they are overseen by the Department of Transportation, not the Parks Department. And in some neighborhoods, they have been met with resistance amid fears that they were a trigger for gentrification.

Simeon Bankoff, the executive director of the Historic Districts Council, called the pedestrian plaza program a “very mixed bag.”

“In some cases, there are tables that are put out, and food carts pop up, and it becomes a space for people who are patronizing food carts instead of just hanging out,” he said.

When the city’s pedestrian plaza program began 10 years ago, it was controversial because it called for blocking off some of the busiest streets in the city if not the world. Ten years later, the program has changed the aura and ambience of the city, making it more walkable and, officials say, safer and cleaner — and not just in midtown Manhattan, where the pedestrian plaza in Times Square served as a high-visibility demonstration project.

City officials say that after traffic was rerouted in Midtown, there were 35 percent fewer injuries from pedestrians being hit by cars and 63 percent fewer injuries to drivers and their passengers from fender-benders. And, in the three years after a plaza was created in Fort Greene, Brooklyn, accidents dropped 53 percent and injuries from crashes dropped 62 percent.

As these figures indicate, the city’s Department of Transportation is reaching beyond Manhattan. Since the de Blasio administration took office in 2014, nine plazas have been created in Brooklyn, two in Queens, two in the Bronx and eight in Manhattan, four of them north of 125th Street.

“DOT broke some eggs when they created this program, and now we’re all making the omelet,” said Tim Tompkins, the president of the Times Square Alliance, the business improvement district that maintains the area and arranges outdoor programs there. “The complex work is how are the ingredients going to be different in Times Square than in Elmhurst?”

Saturday, the city will celebrate the 10-year anniversary of the pedestrian plaza program with a ceremony at Corona Plaza. In that decade, the idea has spread far beyond New York. Pedestrian plazas have been created in Mexico City, Bogotá, Colombia, and Addis Ababa, Ethiopia, with advice from former Bloomberg administration officials who set up the program.

“It’s now copied all over the country and all over the world,” said Samuel I. Schwartz, a former New York City traffic commissioner who is known as Gridlock Sam. “Cities are looking for these opportunities, which is what the reverse of what they used to do when they widened street after street.”

In 10 years of what some officials call “plazafication,” one of the lessons learned is that creating plazas involves more than design. “The key is every city has to invent the exact mechanism that they use because every city has a different structure and every city government has a different relationship with its population,” said Andy Wiley-Schwartz, who was named the assistant commissioner for public space in the transportation department when Michael Bloomberg was mayor.

In New York City, the same goes for neighborhoods. In midtown Manhattan, business improvement districts can contribute to the cost of maintaining the space created when streets are closed — the gardeners who tend the flowers, the trash collectors who pick up litter. But neighborhood groups often lack money for upkeep, so the city set aside more than $1.4 million a year for maintenance, something proponents say is essential if plazas are to do more than change traffic patterns. “In the beginning, there was a good deal of vandalism around the plants, stealing the plants,” said Laura Hansen, the executive director of the Neighborhood Plaza Partnership, an offshoot of the Horticultural Society of New York that has a $1.2- million-a-year contract from the city to maintain 16 plazas outside midtown Manhattan. But the thefts at one plaza, in Brownsville, Brooklyn, stopped as the maintenance continued.

And the regulars in a plaza take on responsibility. She said that a homeless man in one plaza her group maintains — Diversity Plaza in Jackson Heights, Queens — made a sign that said “Please do not sit on the planters.”

Polly Trottenberg, the city’s transportation commissioner, echoed the idea that a public space like a plaza needs to be looked after. “If it’s not tended, it loses its luster,” she said. “That was challenge No. 1."

To some who follow the ins and outs of municipal governance, the plazas are unusual because they were begun under one mayor, Bloomberg, and were continued under his successor, Mayor Bill de Blasio. “Obviously, I came in with the de Blasio administration, and the program was very, very successful,” Trottenberg said. “People loved it, reclaiming streets given over to cars but not really used by cars.”

Pedestrian plazas began to appear in other cities in the 1960s and 70s when suburban shopping centers left older downtowns deserted. The thinking then was that customers would return if there were large, walkable spaces. Cities experimented, closing block after downtown block. Not all succeeded — in 2008, the Downtown Memphis Commission concluded that 85 percent of pedestrian malls had been reopened to traffic, at least partially. The pedestrian plaza in Times Square has had its own history, what with incidents involving an Elmo who unleashed an anti-Semitic rant, a Spider-Man who demanded money from a tourist he had posed with and then slugged a police officer and a Cookie Monster who groped a teenage girl. In 2015, the police commissioner at the time, William J. Bratton, said pedestrian plazas should be done away with.

They were not. But Times Square is different from the other plazas in size and volume, and that affects people’s expectations. “Generally a tourist walks through Times Square and says, ‘Hey, this is cool and fun,'” said Tompkins of the Times Square Alliance. “What we’ve been doing is thinking, how do we tweak the experience so it is more welcoming to New Yorkers. It’s not Bryant Park. We know it’s not going to be a verdant pasture. So our own vision of the space has evolved over time.”

He said there had been “a 1.0 version, a 2.0 version and a 3.0 version” in Times Square. The first, he said, was “creation,” followed by “chaos, when it went from closing the streets to actually building the plaza and then totally unregulated commercial activity, all these hucksters and hawkers out there.” Now, he said, “the question is how you cultivate interesting activities.”

Elsewhere in New York City, even after pedestrian plazas are completed, not everyone is convinced they are an improvement. Samantha Sanchez, who works in a hair salon on Myrtle Avenue in Clinton Hill, Brooklyn, said she was not a fan of the plaza that took shape as new apartment buildings were going up on the block beyond Hall Street. She said it had made the traffic flow more confusing and had drained away the local flavor.

“I feel like Brooklyn’s being taken out of Brooklyn,” she said. “They want a mini-Manhattan. But Manhattan is more convenient for pedestrians. This is not.”

But other plazas in other neighborhoods have drawn the opposite reaction. Sitting in Corona Plaza on a recent morning, Reuben Hernandez said it had brought panache that was like Manhattan’s. “Now I have it here,” he said. “I don’t have to go there anymore.”

Hourizadeh, the optometrist in Corona Plaza, said his patients still have trouble finding places to park. So is the plaza — which the transportation agency built with guidance from the Queens Economic Development Corporation and the Queens Museum, among others — an improvement?

“The quick answer is yes,” he said, although he complained that construction took longer than he thought it should have.

Still, he said, he has a second store a dozen blocks away: “I wish they’d do the same thing there.”