A 14-year-old boy in Lodz, Poland allegedly hacked a TV remote control so that he could control parts of his city's tram system. Sounds like he identified the infrared pulses used to override the track switching. Four trams were derailed but nobody and 12 people were injured. From The Register:
"He had converted the television control into a device capable of controlling all the junctions on the line and wrote in the pages of a school exercise book where the best junctions were to move trams around and what signals to change," (said Lodz police spokesman Miroslaw Micor.)Link (Thanks, Jason Tester!)
"He treated it like any other schoolboy might a giant train set, but it was lucky nobody was killed...
The youth, described by his teachers as an electronics buff and exemplary student, faces charges at a special juvenile court of endangering public safety.