THE SITUATION: It's rush hour, and/or the height of tourist season. You descend the escalators at a station well-trafficked by locals and tourists, look at the board, and see that your train will be arriving in one minute – time to hustle. So, SmarTrip in hand, you rush for the gates – only to be held up by a person who is fumbling around for her ticket or SmarTrip in a big purse, blocking your way. All of the other gates have a queue of a few people behind them. She's not moving. Are you resigned to wait for the purse-fumbler to procure her ticket from her purse, or can you politely ask to go ahead?

Or what about the large groups of tourists and students that clog up the gates and escalators? They're intent on staying together, they're slow-moving, and seven times out of 10, they are comprised entirely of surly teenagers being forced to see monuments and museums when they'd rather be listening to Justin Bieber and furtively making out in the back of their tour bus. Is it rude to force your way in front of a slow-moving group, or is a herd susceptible to cutting?

THE CONSEQUENCES: Usually, individual or collective slowpokes present a holdup of less than a minute – but as frequent riders know, that can mean the difference between catching and missing a train. Think of the collective waste of time if, say, just 100 government workers miss a train this way every day, and another train doesn't arrive for 3 more minutes. That's 1,300 lost hours of work every year, just due to Metro gate-jams. Granted, that's probably a tiny fraction of the time workers lose each year to Twitter and Facebook, but still! Even first-time Metro riders know they will have to pass through those gates. And they have a whole escalator ride, and several dozen yards before they encounter those gates to root around in their bags. We considered calling an efficiency expert to determine the optimal time to begin searching for a SmarTrip based on the volume of a bag, but figured that, being an efficiency expert, we were already wasting that person's time.

THE CHOICES: Sometimes, you don't have a choice – you're just stuck swirling in the sea of humanity that is a crowded Metro stop. But if you're on the escalator and you see a large group ahead, you have time to bound down the stairs and edge your way in front of them to avoid any pileups at the gates. As for a singular gate-blocker, you have several options:

•If the person is struggling with inserting their ticket, offer to help.

•If they're just rooting through their bag, and you can't hop over to another gate without getting in line, give the person a few extra seconds to find their ticket.

•If it takes longer than that, it's likely that he or she will step aside for you.

•If not, and if you see your train coming and want to make a dash for it, you might decide to ask (nicely!) if you can go ahead.