Walt Disney World is famous for its extensive monorail system. Here are some things you may not know about this unique form of transportation, even if you’ve been to Walt Disney World many times.

1. It’s one of the two most popular monorail systems in the world

The Walt Disney World Monorail System carries over 150,000 on a daily basis. There’s only one other monorail system in the world that surpasses its number of daily passengers—Chongqing Rail Transit in China.

The Disney system has a total of three lines, including the two Magic Kingdom ones (Express and Resort) and the single Epcot line. The Express line carries passengers between the Transportation and Ticket Center and the Magic Kingdom, while the Resort line also stops at the various monorail resorts. The Epcot track simple runs in a loop from Epcot to the Transportation and Ticket Center.

2. The system has its own maintenance area near the Magic Kingdom

There’s a maintenance area for the Disney monorails, as well. It’s located northeast of the Magic Kingdom, down the road from the Contemporary Resort.

This area holds up to ten monorail trains at one time. (There are twelve trains total.) At night, the trains are parked here until the next morning, and maintenance checks are performed before they go back out for the day.

Unfortunately, due to space constraints, two trains are left on the track overnight. If the weather is poor, however, these trains are often parked inside the Contemporary Resort instead.

If a monorail train ever breaks down and is unable to be restarted quickly, special tractors are dispatched to pull the train into the service station. These tractors run on diesel fuel, so a power shortage is never an issue.

3. The monorail track is just over two feet wide

Though the track for the monorail seems imposing from afar, it’s actually only 26 inches across. These tracks are actually called “beams,” and they are much thinner than the actual monorail trains, which are a little over eight feet across. The trains are 203.5 feet long and carry up to 360 (though the comfort level at max capacity would be virtually nonexistent).

The small width of the beam probably won’t bother you unless there’s some reason you’d be walking across it. Don’t worry, though; that only happens if the monorail is evacuated due to fire.

4. The monorail is sometimes evacuated during emergencies

For the most part, the monorail ride is one of the most comfortable attractions on Disney property. (And, yes, Disney does count the monorail as one of its attractions.)

However, for a few unlucky passengers, an emergency got in the way of their usually seamless ride. In 1985, a fire broke out in the rear car on the monorail. Authorities believe it was caused by a flat tire that caught fire due to friction. Passengers kicked out windows and climbed on top of the train to escape the fire.

In 2014, a power failure caused a train on the Epcot line to stall on the beam. Passengers were trapped inside the train for over an hour before they were evacuated by Disney personnel and the local fire department.

During an evacuation, passengers will generally use one of three escape routes. There’s a window inside each car that opens from the inside. Passengers can also remove part of the ceiling to reveal a trap door that opens onto the roof (these doors were installed after the fire incident). Alternatively, someone can release the air pressure to open a door from the exterior of the monorail, as well.

Usually, passengers will crawl onto the roof of the monorail and be assisted to the ground by the local fire department. However, if the emergency requires that the entire train be evacuated quickly, guests are directed to walk across the top of the train to the front car, where the pilot attaches a rope. Occupants then crawl down this rope to the beam below. They may need to walk away from the train along this beam, if necessary, which is why the two feet of width may be cause for concern.

Fortunately, monorail emergencies are quite rare, so the evacuation plans are mostly there as a “just in case” measure.