Racing to find solutions to subway flooding 

A flood vent (source: 3EPR)

New York’s subway system is the nation’s busiest, serving 15.3 million people across a 5,000-square-mile travel area. So, keeping it operational under all conditions – including heavy rainfall and hurricanes – is vital the livelihood of people in and around New York City. That is one reason why a field trip was taken to three subway stations as part of New York Water Week.

Done in conjunction with the Metropolitan Transportation Authority (MTA), the field trip showed water professionals the  MTA’s current “toolkit” of flood mitigation devices to protect underground railways from stormwater flash flooding. Attendees experienced a true subway ride, traveling from the Water House to the Bronx, stopping at the 138th Street grand concourse, Third Avenue station, and Longwood Avenue station.

Each location has different resiliency challenges and deployment measures to make them more resilient against rain and flood events. New York MTA representatives presented demonstrations on emerging solutions at each site to highlight progress made since Hurricane Sandy in 2012.

138th Station – The subway stop is in a floodplain, creating challenges. At the location, the MTA team demonstrated a deployable solution attached to the actual subway system. The solution lifts grates, removes handles, and deploy a very large tarp that fits into a stainless steel tract strong enough to withstand a Class 2 hurricane. Another part of the solution is multiple grates with deployment systems. Field teammates hooked levers and rose flaps to cover the subway vents.

Third Avenue – While this station is not in a floodplain, it has water concerns because it sits at the base of a sloping sidewalk. The station suffers from flash floods during heavy rains, as a result. To offset the surrounding area, a few small steps have been taken. First, curbs have been raised a few inches. Self-deploying systems to cover the subway vents to address the immediacy of flash flooding were also shown.

(Source: 3EPR)

Longwood Street – A third unique challenge was shown at the final stop. Longwood Station sits in a low point of the subway line. When water floods into the tunnels, it travels to Longwood Station and settles. It is so serious that they have had several feet of water during significant flash flood instances.

The goal is to prevent water from entering, as well as approaches to remove it when it floods, while not adversely affecting local residents and businesses. So, this particular scenario must balance the subway solution with the community itself.

Racing to a Solution

After visiting all three stations, a Design Sprint workshop was held. Three teams were formed and each collaborated to design novel solutions for the problems shown and quickly developed prototypes.

A jury panel reviewed each idea. While all were promising, a water capture system was selected. Similar to a basin, the system would lie underneath the subway and store water. It would allow the water to be reused in multiple ways. Examples included a gray water system for buildings and geothermal.

The Design Sprint offered a starting point in the race to find solutions for water mitigation issues faced by New York. Many of the solutions shown and discussed can be transferred to other urban areas with similar issues.  

Watch the video of this field visit