It's a high-presence security uptick at some of the metro's busiest stations.
"Sometimes it makes you nervous, but in the evenings, it's kind of comforting," says Molly O'Connor of Arlington, VA.
Authorities call this sudden, temporary influx of 50 heavily armed officers and canine units "Blue Tide" -- short for "Terrorism Identification and Deterrence Effort."
Robert Flint , a District Heights Resident, says: "It's unfortunate, but it's a sign of the times."
But do these kinds of security operations really make people feel safer? Flint believes these actions do help keep bad guys at bay.
"The possibility of them not knowing when the police are actually going to show up makes me feel a little bit safer," he explains.
During this one-day show of force, officers will patrol platforms, inspect trains, and even check garbage cans for devices. However, not everyone is convinced a higher police presence is a deterrent.
Brittany Saunders of Alexandria, VA says: "Anything can happen at anytime, even with the police around. Nowadays, nobody cares. Anything can happen."
Still, with the Fourth of July holiday approaching, most riders say the more police eyes and ears are out there, the more secure they'll feel.
Crime prevention information will also be given out to riders as they make their way throughout the rail system. Officials say that the increased present isn't in response to any specific threat; rather, it's an exercise in awareness and deterrence.
Officials did not say which specific stations would see a higher-than-normal presence of law enforcement.