More than five million people take the subway every day, most of them armed with a smart phone.

When there's a stuck train, a crazed passenger or some other travel headache, riders are quick to share their pain.

"20 minutes later and we have only made it two stops," tweeted a Q train rider.

"Dear @MTA what is the point of an express train if it never moves with any sense of urgency?" tweeted another.

“We’re managing potentially hundreds of tweets an hour," said Jed Poster, a customer communications manager.

The explosion of social media has forced the MTA to monitor Twitter and other platforms for information about train service, and respond in kind.

“What we have to do is just sift through the content and see if it’s worthy of responding. I want to say everyone is, but again, with Twitter you get a lot of people that mention us we have a lot of different terms that will trigger a response," said Deshawn Bolden, a customer service specialist.

With a staff of 17 who work around the clock, the team at the Rail control center respond about 400 times a day helping riders get to their destination. Double that, if it's particularly hectic.

The Tweets range from the specific, like asking when one of the MTA's newest model cars, the R160, will arrive at a particular station, to helpful.

"We received a picture of some hateful graffiti on a bus stop kiosk and we notified bus command of it they responded promptly," said one social media associate.

"A lot of our tweets are just like, where's my next train coming from, where's it at, how long do I have until I get there?" said Tyler Schow, a staff analyst for NYC Transit.

The MTA now receives about 42,000 social media mentions a month, a 28 percent increase in just one year.

And many of the posts are full of anger.

Straphangers are not shy about rage tweeting when their commutes turn frustrating.

"I actually tweeted them like about two, three months ago about my metro card being destroyed at one of the machines and their response was, oh well, contact this number. I was like, well didn’t you think I tried that already," said Delbert Browne, a commuter.

Amid the stream of vitriol, there are messages of gratitude.

“The number of times that we actually help people and they say thank you, and we’ve given them good advice that they’re really appreciative for, those vastly outweigh the ugliness,” said Poster.

But at the MTA's social media desk, he admits, "You have a thick skin."