When the London Underground was new, Queen Victoria was still on the throne, chimneys breathed graphite smoke, and England felt more than two degrees colder than Fahrenheit. Today, about 60% of the subway system, which once sheltered the city from bombardments, is becoming a health risk due to the lack of air conditioning on hot days, when rails can warp due to the heat.
Meanwhile, the New York subway has not known sleep since its founding, but downpours are increasingly interrupting service: platforms turn into pools of water, and ventilation shafts turn stairs into streams of water.
Even the world’s most advanced systems are learning hard lessons about how to build for resilience in the face of increased rainfall intensity and hot days. In 2021, the city of Zhengzhou experienced a powerful flood: about 20 centimeters of rain fell in an hour, the subway resembled a flooded vessel, and on a line that had been in operation for less than ten years, fourteen people died.
“We are discussing metro system issues around the world,” said Eric Wilson, Vice President for Climate Resilience and Sustainable Development Planning at the Metropolitan Transportation Authority of New York. “Tokyo, Paris, and London are currently experiencing such flood events.”
– Eric Wilson
The underground used to be a refuge from city noise, but with climate change it is increasingly under threat: infrastructure built for the last century is not always able to withstand present-day climate pressures.
In 2012, the powerful Hurricane Sandy flooded Manhattan’s oldest and lowest stations, prompting innovative solutions, including the use of inflatable gates to seal tunnels. However, such solutions require upfront preparation and coordination, which are most effective in advance, not during sudden floods that can inundate cities in minutes.
Urbanism for the Underground: A Path to Resilience
Each storm brings new challenges that demand bold solutions in cities around the world. The subway is already submerged below sea level and exposed to higher water levels due to rising oceans. So the need for green initiatives is growing – from more trees to sustainable surface drainage and the use of natural cooling mechanisms.
Efforts are directed at reducing heat load: cities plan to expand greenery, implement urban drainage systems that lower air temperatures and ease the operation of transport networks on hot days.
In the future, subway resilience will depend not only on technical solutions, but also on how well a city can integrate green and water-based solutions into the urban environment: trees, green roofs, drainage with an emphasis on reducing heat emission and maintaining passenger safety even during extreme weather events.
Therefore the development of urbanism for the subway should combine engineering developments with above-ground spaces: adaptive drainage systems, cooler and stagnant air flows, as well as smart cooling and ventilation solutions that will make the subway more reliable in the future.