The race to protect New York’s subway from extreme rainfall
As the planet warms, subway systems around the world have struggled to cope with floods far beyond what they were originally designed to handle.
(The Washington Post)The race to protect New York’s subway from extreme rainfallSubway systems around the world struggle to cope with floodingEvery day, thousands of people walk up these two yellow steps, never knowing they are treading on a key tool in the New York subway’s fight against a rising climate threat.Torrential rainstorms fueled by the warmer atmosphere are increasingly striking the city — creating floods that gush into tunnels and submerge tracks.At least 200 of the city’s 472 stations have flooded in the past two decades, according to data from the Metropolitan Transit Authority.December 19, 2025 at 5:00 a.m. EST7 minutes agoAs the planet warms, subway systems in places such as London and Tokyo have struggled to cope with floods far beyond what they were originally designed to handle. Stormwater regularly seeps into the subterranean networks, cutting off the transit lines that are their cities’ lifeblood. At least 14 passengers were killed in the Chinese city of Zhengzhou four years ago when floodwaters filled their train tunnel.Few places are more susceptible than New York. The city’s sprawling, century-old subway system was built close to the surface and contains more than 40,000 openings through which water can reach the tracks below.A map that shows where floods have been reported in the New York City Subway according to MTA data. The map shows stations that have two or more reported impacts in dark purple and stations that have one reported impact in lighter purple. Stormwater impacts can include such effects as pooled water on platforms and flooded tracks and tunnels. Staten Island Railway not shown.Its vulnerabilities underground are exacerbated by surging moisture in the skies above, a Washington Post analysis shows. The strongest plumes of water vapor the region sees each year — which provide fuel for the most severe storms — are intensifying almost twice as much as the global average. Very heavy rainfall events (producing at least 1.4 inches of rain in a day) have increased about 60 percent since the subway was first built.Yet public transit is also crucial for the fight against rising temperatures, officials say, because it means riders aren’t using cars or trucks that spew planet-warming pollution.This is what it will take to protect the New York subway — and its nearly 1.2 billion annual riders — in an era of escalating floods.Passengers navigate a train platform at Grand Central in New York on Dec. 11.An aging systemLong before the subway was built, before the city even existed, water defined New York. Manhattan was dotted by ponds and crisscrossed by creeks and streams. Wetlands fringed the Brooklyn and Queens borders, expanses of swaying cordgrass and reeds absorbing the rise and fall of tides.As the city grew, the original landscape was obscured by buildings and pavement. By the time subway construction began in the early 1900s, few remembered or cared where water once flowed.Today, that oversight is proving costly, said ecologist Eric Sanderson, vice president for urban conservation at the New York Botanical Garden. When he and his colleague analyzed reports of modern-day inundation from 311 calls and official flood maps, they found that the most susceptible parts of the city are often the sites of former waterways.An image made in 1893 of 116th Street near Lenox Avenue. (Brown Brothers/The New York Public Library)The 116th stop on the 2 and 3 lines, which run along Lenox Avenue in Central Harlem, illustrates the leaky system’s many vulnerabilities.The station sits at a low point in Manhattan’s topography along the path of a former creek. Flood maps from the New York City Department of Environmental Protection (DEP) show how stormwater collects at this spot — generating what the agency calls “deep and contiguous flooding” during periods of intense rain.A historic map of the area around the 116th St. station in Harlem. This map uses data from the Welikia Project to re-create what the region looked like in the early 17th century. The topography and coastline differ greatly from that of modern-day New York City. Tidal marshes and streams are annotated, and, when overlaid with modern Manhattan, a strong correlation with flood-prone areas of the subway system can be seen.This map of the same area as the before imagery shows what parts of the city's infrastructure are prone to flooding. When paired with the 17th-century re-creation, a strong connection to the flood-prone stations can be seen.“It’s not like you can erase the ecological factors that led to there being ... a creek there,” said Sanderson, who has spent more than a decade studying the city’s pre-Colonial landscape. “And climate change is supercharging those factors.”Like most of the original subway, the 116th Street station was built using the “cut and cover” technique, in which workers dug a trench, constructed the tunnel, then rebuilt the street on top.This graphic is an illustration of the intersection of 116th Street and Lenox Avenue, including a cross-section of the subway station below the street level. It shows how the intersection is at risk of flooding, including the station's entrances and vents. The illustration also shows how water drains off the platform, through the tracks, into a pump room located off the platform and into the city's sewer system. According to the DEP, this intersection can become submerged even during a “limited flood” scenario, when rainfall rates are 1.77 inches per hour.Water running off the sidewalk can drain into the station’s four entrances and several sidewalk grates, which are the station’s primary method of ventilation.116th Street station, Manhattan, Sept. 1, 2021Pans underneath the vents collect rainwater, but they can overflow in a deluge, spilling torrents onto the platform below.As water runs off the platform into the track bed, it mixes with floodwaters flowing from elsewhere in the tunnel. If water on the tracks rises as high as the electrified third rail — which supplies power to the trains — it becomes unsafe for subways to run.To avoid that scenario, a drain beneath the tracks carries water to a nearby sump pit. But the drain can become clogged with trash.When the sump pit fills, it activates pumps that push the water into the city’s sewer system. Two of the pumps at 116th Street are more than 100 years old and can handle only a fraction of the rainfall the city now experiences.After decades of budget crises and deferred maintenance, much of the subway system is outdated and in disrepair, the MTA acknowledges.But when it comes to storms, aging pumps are its “Achilles’ heel,” said Eric Wilson, the agency’s senior vice president for climate and land use planning. Of more than 250 pump rooms in the system, 11 percent are in poor or marginal condition, according to a 2023 assessment.At 116th Street, the struggling pneumatic pumps emit a shuddering screech every time they turn on.“You’re looking at a relic, basically,” said Juan Urena, a superintendent in the Department of Subway’s hydraulics division. “It’s time to upgrade.”MTA workers look into the sump pit at the 116th Street station on Oct. 17. The decision to put the subway underground stems from the “Great White Hurricane” of 1888, which killed about 200 people in New York and stranded roughly 15,000 people on the elevated trains that were then the city’s primary transit system. Freezing passengers fled one snowbound train by climbing down a ladder — but only after they paid the ladder’s owner 25 cents each.The catastrophe left residents aghast that their modern metropolis could be brought to its knees by the weather. Within three years, the state had authorized construction of a subterranean transit system.Water has posed a problem from the beginning. Groundwater seeps through tunnel walls, requiring the MTA to pump at least 10 million gallons out of the system every day. When it rains, New York’s tall buildings and paved surfaces prevent water from seeping into soils, causing it to run off into subway tunnels instead.Yet climate change has made the challenge worse, officials said. Plumes of warm, waterlogged air frequently stream out of the tropics and make landfall in the city, dropping large amounts of rain faster than the landscape and infrastructure can absorb it.Most parts of New York’s combined sewer system, which funnels both stormwater and sewage, are designed to handle up to 1.75 inches of rain in an hour. When many of the system’s components were installed more than 50 years ago, that intensity of rain could be expected roughly twice a decade. But a rain gauge at Central Park has recorded rainfall exceeding that threshold five times in the past five years.This is a line chart of annual maximum rainfall at the Central Park gauge. It shows inches per hour since a little before the 1950s. The combined sewer system was designed to take in 1.75 inches per hour at its upper limits. The line chart shows how, in the past few decades, that has been more often exceeded by rainfall averages.“The sewers were designed for a climate we no longer live in,” said Rohit Aggarwala, the city’s chief climate officer and DEP commissioner.When a strong moisture plume swept into the city on July 14, unleashing 2.07 inches of rain in one hour, the sewer system was quickly overwhelmed. Untreated stormwater backed up into streets and homes. Water rained through subway grates, streamed down station stairwells and seeped through cracks in the walls.The overtaxed sewers couldn’t take in additional water from the MTA’s pumps and instead became a source of flooding. At the 28th Street station, water burst through a manhole cover on a train platform, creating a geyser that drenched passengers waiting for the uptown 1 train. (The city welded the cover shut soon after.)“It’s an incredible challenge for any city to have to face,” said Bernice Rosenzweig, an environmental scientist at Sarah Lawrence College and a lead author of the New York City Panel on Climate Change. “The bad decisions were made generations ago, and now it’s figuring out how to deal with that in a fully built-out and operating city.”A manhole cover at the spot where massive flooding took place at the 28th Street station.The worst-case scenarioRosenzweig still remembers stories that emerged from the Zhengzhou subway flooding.Amid the heaviest downpour ever observed in China, water from a collapsed drainage ditch surged into a subway tunnel during rush hour. Survivors spoke of standing on seats and lifting children above the steadily rising water. People began to vomit and faint from lack of oxygen as they exhausted their dwindling pocket of air.The situation in China, which stemmed from a combination of extreme weather, infrastructure failures and human missteps, is not completely analogous to what might happen in New York, Rosenzweig noted.“But it was an important event for city managers and emergency managers to show that it’s not just the nightmare scenario of someone who studies natural hazards for a living,” she said. “It’s something that can happen and has happened, and it’s not unrealistic to plan for those worst-case scenarios.”When the remnants of Hurricane Ida lashed the New York region just over one month later, it underscored Rosenzweig’s worries. At its peak, the storm dropped a record-breaking 3.46 inches in a single hour — about twice the intensity of rainfall the city’s stormwater systems are designed to handle.The MTA’s Juan Urena looks over an antiquated pump room at the 116th Street station on Oct. 17.NEW YORK, NY, US, October 17- MTA workers look over an antiquated pump room at the 116th St. Station in New York, on Friday, October 17, 2025. Increasing rainfall has caused flooding in New York subways, a problem the city has scrambled to address. Photographer: Victor J. Blue for The Washington PostNo injuries or deaths were recorded in the subways during Ida. Yet all but one of New York’s 36 subway lines were shut down, according to an after-action report, and roughly 1,250 passengers had to be evacuated from the system. Damage to MTA infrastructure totaled $128 million.The full economic toll of transit disruptions is probably even greater, research suggests.“It is the absolutely vital organ of the region,” said Jamie Torres-Springer, president of MTA construction and development.The subway is also important for fighting climate change, he noted: By keeping cars off the street, the MTA estimates that it avoids about 22 million tons of carbon dioxide emissions each year.Yet floods make it harder for New Yorkers to get where they need to go. Subway service was disrupted due to flooding at least 75 times between January 2020 and September 2025, according to a Post analysis of MTA alerts.There’s no simple way to stop heavy rains from spilling into the system, Torres-Springer said.Though the MTA dedicated nearly $3 billion in state and federal funds to implement coastal resiliency measures after Hurricane Sandy ravaged the system in 2012, those protections don’t shield against inland flooding, he noted. The tunnel doors and grate covers developed after Sandy must also be deployed with hours or days of advance notice — precluding their use during sudden cloudbursts, like the July 14 storm.Outdated pipes in the pump room at the 116th Street station.Stemming the tideInstead of racing to respond to an approaching deluge, the MTA has adopted a sprawling set of interventions that can protect the subway system day in and day out. In a five-year capital plan passed this spring, the agency committed an unprecedented $700 million to new stormwater defenses.Much of that funding will go toward upgrading at least a dozen pump rooms, including the one at 116th Street. New pumps are made of stainless steel and can handle much more water per minute than their older counterparts, Urena said.But many solutions are lower-tech — what Torres-Springer calls “tactical” interventions that can be implemented one by one, gradually plugging the system’s thousands of leaks.By adding one or two steps to station entrances — as the agency is doing at 116th Street — the MTA aims to protect places that used to get drenched with every storm.New raised grates, sometimes topped by bicycle racks or benches, can prevent puddles on the surface from falling onto passengers below.At a few stations, including 116th Street, the agency has sealed vents with temporary covers until more permanent improvements can be installed.In some places, stopping floods is as simple as keeping debris out of the drains that siphon water on the tracks into station pump rooms. Since 2017, the MTA has maintained a catalogue of nearly 10,000 drain boxes scattered across the subway system. The agency has said it aims to clean at least a quarter of them every year.As of this month, the MTA has installed or set aside funds for flood defenses at 110 of the 200 flood-prone stations, according to a Post analysis of agency data. But 22 stations that have flooded more than once are not on its list of targets. Several of these stations, most of which are in Brooklyn, were among those inundated during the July 14 storm.A 2023 report from New York’s state comptroller also faulted the MTA for failing to complete several flood-proofing projects and for inconsistently following extreme-weather protocols.In a statement, MTA spokesperson Mitch Schwartz said that vulnerable stations not targeted in the capital plan might still receive flood defenses as part of other upgrade work.“We have never moved faster to keep this system safe from extreme weather,” he said.But the MTA can’t hold back surging floodwaters on its own, Torres-Springer said. The fate of the subway is inextricably linked to that of another massive, aging underground system: the sewer.The DEP recently adopted a requirement that all new stormwater infrastructure be capable of withstanding 2.15 inches of rainfall in an hour. The agency has directed about $10 billion to drainage network improvements, expanded sewer mains and underground tanks capable of storing excess water during storms.With a limited budget and more than 7,400 miles of sewer pipes to maintain, Aggarwala said, the DEP’s priority is preventing water from getting into people’s homes, where it can destroy possessions and threaten lives. Subway disruptions due to flooding, he added, are more temporary.As the skies above New York grow ever warmer and wetter, keeping water out of the subway will also involve restoring it to the surface where it originally flowed.Ecologist Eric Sanderson.Guided in part by Sanderson’s research on New York’s original ecology, city agencies are trying to uncover hidden creeks and wetlands — creating “bluebelts” that can absorb excess rainfall during severe storms. By alleviating pressure on the sewer system and giving runoff an alternate place to go, officials say that these projects can curb flooding in neighborhoods and subway stations alike.The initiative is a long-overdue reversal of the impulse that led New York to pave over waterways and bury the transit system in centuries past, Sanderson said.“A city that works with its nature,” he said, “is going to be a city that lasts longer for its people.”About this storyTop videos by Wynter Gray/Storyful; @nuevayorkypunto/Spectee; Paullee Wheatley-Rutner/Storyful; Ayeraye Akosua Hargett/Storyful; and @anjalitsui.Design and development by Talia Trackim. Additional code by Frank Hulley-Jones. Editing by Simon Ducroquet, Roger Hodge, Betty Chavarria, Dominique Hildebrand, Juliet Eilperin and John Farrell. Copy editing by Rachael Bolek.MethodologyTo examine trends in heavy rainfall in New York City, The Post analyzed 130 years of rain gauge data from the National Oceanic and Atmospheric Administration’s National Centers for Environmental Information weather station in Central Park. To define what counts as a heavy rainfall day, The Post used the period from 1895 to 1924 to find the threshold for a 95th percentile precipitation event. Days with at least 0.5 millimeters of precipitation were included. Using a simple linear regression, The Post measured the change in frequency of the 95th percentile rain events at the station from 1895 to 2024.The analysis showed a significant positive trend in 95th percentile rain events, with the number of days each year with heavy rainfall increasing by nearly three days, a roughly 60 percent increase.Carolien Mossel, a PhD candidate in the CUNY Graduate Center’s earth and environmental science department, provided guidance on the data and analysis of hourly precipitation amounts for Central Park from May 1948 to August 2025.To investigate global changes in extreme precipitation, The Post measured the amount of water vapor flowing through Earth’s atmosphere, a metric called integrated vapor transport (IVT). The analysis also identified days and locations where heavy rainfall coincided with high IVT. See more about The Post’s methodology for the IVT analysis here.To map how present-day New York City would have looked in the early 17th century, The Post used data from Eric Sanderson’s “Before New York: An Atlas and Gazetteer” (Abrams, 2026), courtesy of the New York Botanical Garden.
