Miami International Airport is American Airlines’ primary Latin American and Caribbean hub, and its sprawling 50-gate Concourse D is a mile from one end to the other. To ease the transfer between gates, many travelers jump on the Skytrain, which runs most of the way through that concourse. However, that train won’t be an option for travelers in the months ahead.
MIA has shut down the Concourse D Skytrain because the structures that support the train's tracks show "accelerated deterioration of the concrete," according to this Miami Herald report. The 13-year-old track system is designed to move 9,000 people per hour.
The airport has not said when the train will reopen. Its Skytrain online-information pages suggests leaving 30 minutes for a walk from one end of the terminal to the other and “for assistance, look for the white golf-cart trolleys” that travelers can flag down for a ride. Keep in mind, though, that the terminal handles 80,000 people each day.