Problems with the Metrocard

Over the Christmas holiday, my family, along with friends of my younger daughter, spent time in New York City. One day, the nine of us took the subway from Chinatown to midtown. The MTA (the transit authority for New York City) has an arrangement under which a person can purchase five subway trips (at $2 each) and get a sixth trip free. "Great," I said to myself, "there are nine of us, so I can put $30 on a MetroCard, and get 18 trips rather than 15--that's just enough to get the nine of us up to midtown and back."

At this point, I'm thinking I'm a genius. I put $30 on a single MetroCard, proceed to the turnstile, and begin swiping it. Each time I do so, one of our group goes through. The first four go through fine. However, when I swipe it the fifth time, the turnstile locks up and displays a message, "transfer limit exceeded." I swipe it again, and get the same message. Not wanting to take chances, I get more MetroCards and get the rest of our group through.

After we arrive at our destination (Bryant Park, behind the Public Library), I go back into the station and ask the booth attendant what happened. She told me that the MetroCard has a four-person limit--that is, a maximum of four people can use a single MetroCard. That's why, when I swiped it the fifth time, I received the message.

Looking back, I see two issues with the MetroCard limitation. First, nowhere are we told about this four-person limitation. I couldn't find any signage in the station about it, nor did I see any reference to it on the MTA web site www.mta.info Second, the text of the error message doesn't really convey the issue. If it had said, for example, "Maximum passenger limit exceeded" it would have been clearer.

Apply these lessons to your job. If you're designing a computer system, make sure your error messages are meaningful. If you have limits to your process, make sure people know about those limits.

Even if you're not designing a computer, these principles still apply in communicating with others. Be sure they understand you, and try not to surprise them. In other words, set their expectations.