One side effect of living in Baltimore is that my tolerance level for unusual behavior has gone sky-high. That zombielike man stumbling in circles down the block? Probably just another friendly neighborhood crack addict. That screaming chick? She’s just greeting passersby in her own special way.

So when I say there was a really freaky dude on a Red Line train to Silver Spring with me last week, I’m saying he was really freaky. He boarded my car at Union Station and started asking people for money. That’s easy to deal with — I just buried my face deeper into that day’s Express to avoid eye contact, and he walked on by. But another woman a few rows ahead gave him a look that he didn’t like at all.

And that’s when he started screaming. He also violently struck the walls of the car, and grabbed ads and ripped them to shreds. As we pulled into the NoMa-Gallaudet U station, everyone sitting around me gathered their things and got the heck out of there. A bunch of us entered the next car back, and I went straight for the emergency intercom button to report the incident. The driver held on the platform briefly, and securing came and got the guy off the train.

While we waited, and everyone stared through the doors at what was happening, a woman mentioned the guy had been terrorizing passengers on this car a stop earlier. But no one had thought to alert the driver, which makes me think it’s time for a quick refresher course on public transit safety.

Metro Transit Police deputy chief Ron Pavlik says everybody’s danger threshold varies, and a situation can seem very different during morning rush than at 2 in the morning, or if you’re among a group of guys rather than a woman traveling alone. “But if the hairs stand up on the back of your neck,” he says, “call us.”

You can do that by hitting the intercom, as I did. An indicator light will tell the driver exactly where you are on the train and he or she can notify police to be waiting when you arrive at the next stop. (Because it’s difficult to do discreetly, Pavlik generally discourages calling when you’re in earshot of the individual you’re reporting. “Why put yourself in harm’s way? But if someone’s being assaulted, you have nothing to lose,” he says.)

Another option is calling Metro Transit Police directly, and Pavlik recommends programming in the number (202-962-2121) into your phone so you’re ready just in case. It’s not that dialing 911 is wrong, but the dispatcher will often turn the call over to Metro, so it can be faster to skip the middleman.

Either method is bound to be more effective than simply hoping the scary, unstable guy just goes away.