Mayor Bill de Blasio said Thursday that New York City could expect to see an increase in motor vehicle traffic in June when the city begins to gradually reopen businesses following the COVID-19 shutdown, a remark that renewed concerns about the progress the city has made in recent years toward becoming less congested and car-reliant.

During his daily press briefing, de Blasio estimated that between 200,000 to 400,000 New Yorkers could return to work once the city reopens, which he expects will occur sometime in the next two weeks. He was later asked about whether the city was prepared to have those workers return to using public transit.

"For the next few months, people are going to make their own choices. Some are going to come on mass transit and some are not," he said, saying that he understood that some workers may still be "uncomfortable" with the idea of taking public transportation.

He added that while the city was still committed to mass transit, the "short-term reality" may be a spike in drivers.

Apart from an overnight cleaning subway regimen ordered by Governor Andrew Cuomo earlier this month, the MTA has yet to announce how it plans to ensure the safety of riders, whether it be through increased service or distribution of masks and gloves. De Blasio said he was planning to meet with MTA chairman Pat Foye on Thursday to discuss how much ridership the subways could handle in the first phase.

City Council Speaker Corey Johnson once again faulted the mayor for the city's slow recovery planning.

"The city should have a corresponding improvement in bus service and protected bike lanes planned already," said City Council Speaker Corey Johnson. "We should have spent the last two months planning for this. Now we're a few weeks away from hundreds of thousands—and eventually millions—of New Yorkers restarting their commutes and not knowing how to get to work safely."

He added: "We need a forward-thinking transit plan that ensures fear of mass transit during this pandemic doesn't led to carmageddon."

Transit experts agreed with that assessment and warned that an increase in car traffic could have a cascading effects on public health through increased pollution and density, the very conditions that have made low-income New Yorkers more susceptible to coronavirus infection and complications from the disease.

"The reality is that without a robust transportation plan for recovery, we will have chaotic grid lock and it will fall hardest on the people who are most vulnerable," said Danny Pearlstein, the policy and communications director for the advocacy group Riders Alliance.

Among the gaps in the mayor's logic, according to Pearlstein and others, is the impact an increase in car congestion would have on essential workers. Recent data has suggested that essential workers using mass transit have been more reliant on buses, which experts say reflects both a preference and the typically low-income, transit-starved neighborhoods where those people live.

Subway service has also become more limited. On May 6th, the MTA implemented its unprecedented closure of the subway system between the hours of 1 a.m. and 5 a.m. But while both subway and bus ridership have ticked up in recent weeks, bus ridership—which has been effectively free of charge under the MTA's back door boarding only policy—has surpassed the number of subway commuters in recent weeks. Daily bus ridership is now at 700,000, compared to 600,000 trips on subways, where ridership plummeted by 90 percent in April.

Kate Slevin, a senior vice president for the Regional Plan Association, and others argued that the new realities brought on by the virus should have the city looking to speed up buses and, as part of that, discouraging car use.

"This is vitally important," she said. "The length and duration of exposure in confined spaces is a factor in transmission."

For transportation advocates, there are already worrying signs that the lack of clear direction from de Blasio has only enabled more car use. The New York Stock Exchange, which had a limited reopening on Tuesday, said it would prohibit its employees from taking mass transit.

Danny Harris, the executive director of Transportation Alternatives, whose offices, like the Stock Exchange, are also located in the Financial District, said the mayor needed to send a stronger message to employers.

"The Financial District is already a place where you can barely walk around," he said. "Where are those cars going to go?"

Furthermore, under the administration's initial round of budget cuts, both the city's plan to add 80 more miles of protected bike lanes and to increase bus speeds will lose critical funding over the next two years.

Despite anecdotal reports of more city residents now considering buying a car, car dealers say sales are down, and the expenses and hassles involved with car ownership means it is not an available option to most New Yorkers. A little less than half of all New York City households own a car, according to Slevin.

"There’s not the physical space nor is there money in people’s bank account," she said.

Other large cities, most notably London and Paris, have explicitly ruled out a return to cars in the wake of the pandemic. A recent report by London officials on that city's financial district said, “Any meaningful return to the workplace will need to be primarily by walking, cycling and public transport.” Meanwhile, Anne Hidalgo, the bike-loving Parisian mayor who has often been used as a foil to de Blasio, called an invasion by cars and pollution "out of the question."

San Francisco, meanwhile, has increased bus service under its reopening plan.

In response to comparisons with other cities, de Blasio has frequently argued that New York City's density as well as the unmatched severity of the crisis forces him to be more cautious about adopting new policies.

"We have a lot here that makes what we do very, very sensitive," he said on Wednesday. "Small steps can have a very big impact when you're talking about over 8 million people and job one is safety and health and not allowing that boomerang. So, I really think it is actually exactly right to say we're watching what other people do; we watch a lot of people do things in easier circumstances and then we decide what makes sense for us."

But "complete streets" advocates like Harris point out that the city has already undertaken some of the most ambitious transportation initiatives in the country, from the creation of the 14th Street busway to the expansion of protected bike lanes and pedestrianization of Times Square.

"Our consistent problem is we can’t scale our success," he said. "We don’t have to prove a model. We just have to scale the incredible things New York City has already done."

"The pathway to the recovery needs to be on city streets," he added.

An earlier version misstated the proportion of New York households with cars. The majority are carless.