The US Department of Homeland Security is testing how gas spreads inside the intricate network of the New York subway to better understand the danger associated with a terrorist attack.
On Monday, researchers released a harmless gas at three of the busiest stations on the Big Apple’s underground network - Grand Central Terminal, Times Square and Penn Station.
For the whole week, authorities will be monitoring whether traces of the gas could be detected at any of the pre-selected 55 stations around the Manhattan area. The researchers will be collecting samples every four hours to understand the propagation of the gas within the network. Gaining better understanding of the spread of gases will help the authorities assess risks associated not only with a possible terrorist attack but also with any accidental leak or contamination.
"These tests are designed to gather data about how airborne material will travel through subway systems and the trains and how quickly they will move," said John Verrico, a spokesman for the department's Science and Technology Directorate, which sponsored the test along with the Office of Health Affairs.
Commuters were left somewhat confused on Monday morning, seeing men and women in orange vests inside cordoned off areas.
"I've heard that they've done it in the past and it sounds like it should be very beneficial," said Amy Aziz, an artist from New Jersey.
For some, the scenes brought to mind some rather unpleasant memories.
"It's something that we know is a possibility but we don't want to think about it because we don't want it to become a reality," said Doris Altman, a New York City subway commuter. "But it's really frightening."
The test is part of a five-year program that began in 2012 to develop methods to protect urban transit systems in the event of an attack or accidental contamination. Previous tests were conducted in New York, Washington D.C. and Boston.
With 469 stations, New York’s underground is the largest rapid transit system in the world. Its 34 lines cover 375km, which also makes the system one of the longest in the world.