Elevated Ventilation Grates for New York City’s Subway System

New York City’s Metropolitan Transit Authority (MTA) installed raised ventilation grates at 25 different locations throughout the city in order to reduce flooding of their subway system. Similar strategies could be used for underground highway assets, such as tunnels, where ventilation systems are at risk of flooding.

In August 2007, a severe rainstorm caused catastrophic flooding of the New York City subway system. During the storm, nearly 5 inches of rain fell within two hours. Because ventilation grates were flush with the sidewalk, large volumes of stormwater flowed directly into the subway stations. Many stations were completely overrun with water and forced to close, leaving 2.5 million riders stranded or delayed. The flooding was particularly extreme in Queens, where stations are located only a few feet underground.

To prevent future catastrophic floods, MTA retrofitted approximately 1500 ventilation grates, installing raised structures in flood-prone areas like Hillside Avenue in Queens and near the 79th and 86th Street stations in Manhattan. The new grates look more like sculptures, made from stainless steel and shaped with curves of varying height. Their artful design was intended to reference stormwater and sea-level rise. Many of the grates also incorporate benches or bike racks.

Functionally, the steel structures act as a protective collar for the ventilation grates. They were constructed so that the lowest part of each unit is able to hold back 6 inches of water. With the raised design, stormwater will be channeled away from subway stations and into proper storm drains. 

MTA funded this project as part of its flood prevention initiative, allocating $31 million to the retrofits. The project was completed in 2009.

More recent extreme weather events, including Hurricane Sandy, have caused MTA to increase its efforts to protect or adapt its vulnerable infrastructure and make modifications to operations that will restore service to normal faster after an extreme event. MTA was awarded over $1.5 billion from the Federal Transit Administration’s competitive resilience grant program (funded through its Emergency Relief program) after Hurricane Sandy, and is using the funds for many resilience projects, including a number of new and additional flood protection measures for street level openings to the subway system.


This Adaptation Clearinghouse entry was prepared with support from the Federal Highway Administration. This entry was last updated on January 29, 2016.


Publication Date: 2009

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