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Lyle Lanley is a con artist and shyster who sold faulty monorails to several towns, including Springfield.
 The con
The "marks" in Lanley's con scheme were towns with a lot of money. Lanley would visit a town and make a sales pitch for his monorails. After the town bought the monorail, Lanley would open a monorail conductors' training school, which was really a farce and provided very little in the way of real training. At the end of the school, Lanley would either select a random student or the least qualified in the class to be the conductor (his exact decision-making method isn't known).
After the monorail was built and a conductor selected, Lanley would set up a huge opening ceremony with a celebrity presiding, then leave (with the town's money) while everyone's attention was focused on the opening ceremony and the celebrity. The monorial, due to shoddy materials, would typically crash on its first run, causing loss of life and extensive property damage, and leaving the town financially ruined. Meanwhile, Lanley would be living it up on a resort vacation—bought and paid for with the "mark" town's money.
 In Springfield
In Springfield, Lyle Lanley interrupted a town meeting when the people were trying to decide how to spend three million dollars the town had collected in fines from Mr. Burns. The town was on the verge of voting to use the money to repair Main Street when Lanley successfully made his sales pitch for the monorail. At the conductors' training school, Lanley chose Homer Simpson to be the conductor, seemingly at random as he (Lanley) walked out the door on the last day of class. The monorail opening ceremony featured celebrity guest Leonard Nimoy, who wowed the townspeople by joking that the monorail could do at least Warp Five. After the first run started, the monorail's throttle broke and its brakes failed, leaving the monorail speeding out of control. Monorail conductor Homer saved the day, however. He took the "M" from the "Monorail" sign and used it as an improvised anchor, embedding it in a giant metal donut atop a donut shop and stopping the monorail without serious injury to the passengers.
Lanley, meanwhile, boarded a plane for Tahiti, looking forward to his next vacation. His plans went awry, however, when his flight made an unscheduled stop in North Haverbrook, one of his previous monorail "mark" towns. Apparently alerted to Lanley's presence, a crowd of locals boarded the plane and attacked him, at least beating him up as Lanley was heard screaming and the plane was seen rocking back and forth. Lanley's ultimate fate is unknown, but as he has not been heard from since, it is possible that he was killed by the people of North Haverbrook.