The New York City subway was inundated with rain on Monday night from severe storms, upending rush-hour commutes as water gushed onto platforms and trains and, in one station, shot up from a manhole like a geyser.
The subway system, which is more than a century old, is relied on by millions of passengers daily and weaves together the city’s neighborhoods. But it has a longstanding infrastructure problem that is only getting worse as rainfall becomes heavier and more frequent because of climate change.
The Metropolitan Transportation Authority, the state agency that runs the transit system, has already invested billions of dollars into climate resiliency measures. But there is no easy fix for subway flooding, and it could take years of cooperation among various government agencies to keep the subways dry, transit experts said.
On Monday, 20 stations were closed while 16 others had delays or partial closures. And as the rainfall deluged some stations but left others relatively unscathed, it demonstrated the unpredictable and hyperlocal nature of how flash flooding affects the city.
Riders like Larry Oquendo, 67, prepare for the worst when they see heavy rain in the forecast. A few years ago, he was stuck at a flooded station where people and rats alike scampered up the stairs to avoid the rising waters.
On Monday night, he canceled his plans to get on the subway. “I knew it was going to be bad,” Mr. Oquendo said. “So I ain’t traveling.”
The M.T.A., which operates the 472 subway stations and Staten Island’s 21 rail stations, said that, despite the shocking scenes on Monday, the system remains durable, and service on subway trains, buses and commuter railroads was back to normal by Tuesday morning.
What causes the subway to flood?
Flash flooding is worse in environments with a lot of impermeable surfaces like asphalt and concrete. The water has nowhere to go except down a drain. And in New York City, those drains lead to a very crowded and old underground system of pipes and tunnels that were not designed for 21st-century storms.
“It is now the case that five of the most intense rainstorms in New York City’s history have taken place in the last four years,” said Rohit Aggarwala, the city’s climate chief.
On Monday, 2.64 inches of rain fell in Central Park, shattering the previous July 14 record of 1.47 inches, which was set in 1908.
Every opening in a subway station, from a staircase to an elevator shaft, is a means of entry for rainwater, said Klaus Jacob, a geophysicist and professor emeritus at Columbia University who has worked with the city on subway flooding issues.
There are 39,000 open grates that ventilate the subway, and many of them must be closed by hand. And while the M.T.A. is developing automatic closures for those vents, it will be expensive. The transit agency has projected it will need an additional $6 billion over 10 years for weather resiliency upgrades, only a portion of which has been funded.
The city’s sewer system, like the subway, is more than 100 years old. About 60 percent of New York City has what is known as a combined sewer system, in which a single pipe carries both storm water runoff and sewage, according to the city’s Department of Environmental Protection.
This system can handle only about 1.75 inches of rain per hour, and Monday’s storm far exceeded that.
“What happened last night is really quite simple,” Mr. Aggarwala, who also heads the environmental protection department, said on Tuesday. “The pipes were designed for a certain amount of water. A lot more water fell from the sky.”
Janno Lieber, the head of the M.T.A., said the sheer volume of rain accounted for the scene Monday night at the 28th Street station at Seventh Avenue, where witnesses described a brown geyser of water spewing from a manhole cover. The flooding was exacerbated by low sidewalk curbs that allowed water to race from flooded streets into the station.
“The system is not a hermetically sealed submarine,” Mr. Lieber said.
Dr. Klaus added that the M.T.A. has made efforts to prevent coastal flooding, but has yet to effectively prevent rainwater from pooling at other low points in the city’s topography. This is a particular problem in some areas that rise and dip, including along Broadway in the Bronx and Manhattan, close to the No. 1, 2 and 3 lines.
There are also parts of the subway system that are below the water table, requiring the M.T.A. to pump between 10 million and 13 million gallons of water a day from the tunnels, even during dry weather. The water makes its way into the sewers and the city’s water treatment facilities.
But on Monday night, more than 15 million gallons were pumped out, Mr. Lieber said, in part because of the city’s backed-up sewage system (which then, in turn, received the pumped-out water).
The M.T.A. and the Department of Environmental Protection said that the two agencies’ initiatives to improve the city’s underground pipes and subway tunnels will cost billions of dollars and take decades. Work on the most crucial sewer projects, Mr. Aggarwala said, will cost his department $30 billion. The annual budget for sewer projects is $1 billion per year.
What is being done to prevent future flooding?
Since storm surge from Superstorm Sandy in 2012 scrambled the region’s transit systems, the M.T.A. has invested $7.6 billion in resiliency improvements, such as raising infrastructure higher off the ground, fortifying subway entrances and sealing 8,200 leaks.
But when the remnants of Hurricane Ida hit New York City in 2021, the event showcased a more frequent flooding threat: extreme rainfall. Warm air can hold more moisture, so global warming means more dramatic and disruptive storms.
In April, Gov. Kathy Hochul approved a $68 billion, five-year capital plan for the M.T.A. that includes hundreds of millions of dollars to protect the subway from extreme weather.
The transit agency has budgeted $700 million through 2029 to add resiliency features both at street level and inside subway stations. The work includes raising stairs and vents near entrances, where water can rush in, and improving more than a dozen “pump rooms,” where storm water is sucked out of stations. In all, the city has 254 pumping stations.
The environmental protection department has focused on major sewer upgrades — including a $390 million project in Brooklyn — as well as green infrastructure projects and cleaning the city’s 150,000 storm drains, Mr. Aggarwala said.
Monday’s storm was considered a “moderate rain flood scenario,” said Kate Slevin, the executive vice president of the Regional Plan Association, an urban planning think tank. In a more extreme storm, the city could expect close to 20 percent of all subway entrances to be affected by flooding, according to the association’s analysis.
Though climate change has not been a major focus of this year’s mayoral election, some of the candidates made reference to it in statements on Tuesday about flood risks and how the city should manage them. Assemblyman Zohran Mamdani, the Democratic nominee, said on social media that “we must upgrade our infrastructure for this new climate reality.” Former Gov. Andrew M. Cuomo, who is running as an independent, said M.T.A. resiliency projects “should be a priority in capital plan negotiations” and should be “expeditiously managed to completion.”
Curtis Sliwa, the Republican candidate, blamed reckless development made worse by Mayor Eric Adams’s “City of Yes” housing plan and said he would use “every lever of power to push for real accountability.” At a news conference, Mr. Adams, who is running for re-election as an independent, reminded New Yorkers that storm water threatens more than the subway: “flash floods can fill streets, stairwells and basements in minutes, often with little or no warning.”
Wesley Parnell contributed reporting.
Stefanos Chen is a Times reporter covering New York City’s transit system.
Hilary Howard is a Times reporter covering how the New York City region is adapting to climate change and other environmental challenges.
Winnie Hu is a Times reporter covering the people and neighborhoods of New York City.
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