from the same article - it explains the automatic safety mechanism for stopping a monorail that get too close to the one in front of it...
so i wonder what happened here....sounds like a technical problem..
here's what it says in the article:
According to a former Walt Disney World monorail driver, the vehicles were outfitted with a safety system called Mapo. The former driver, who said he drove the current Mark VI monorail trains, said as soon as the monorail train gets within two checkpoints of another train, it automatically stops.
The former driver said he believes there are about 150 to 200 feet between checkpoints. He said drivers whose monorail train had to be shut down three times were removed permanently from their position.