TV remote control derails trams [Update]

According to several media reports, a 14-year-old Polish schoolboy converted an infrared television remote control so that he could move the points of the Lodz tram network and succeeded in derailing at least one tram. He is said to have told police that he only wanted to play a trick.

The boy is alleged to have broken into the city tram depot in order to get information and equipment that would let him build the infrared device. His teachers have supposedly described him as an exemplary pupil and an electronic genius. He says he changed the points three times, and one tram was derailed. But, according to the Lodz police, four trams were derailed and the drivers of others had to resort to using their emergency brakes, causing injuries to passengers.

The chaos is said to have erupted on Tuesday last week. One driver wanted to turn his tram to the right, but could not prevent it from turning left. This caused the rear waggon to jump off the track and collide with another passing tram. The boy will now have to appear before a juvenile court, say the Lodz police, charged with endangering public safety.

[Update] Further background information has emerged. In an interview with Gazeta.pl (Polish text), Dr. eng. Slawomir Baranski, assistant professor in the electric traction team at the Polytechnic of Lodz, commented "... On the crossroads where the accident happened there is an infra red system. It works similarly to a TV remote controller. The motorman arriving to a crossroads turns on his transmitter when he's in the right place. ... It's very simple system with over a dozen years of history."

There are apparently no interlocks or fail-safes, and it has been known for some time that even an unmodified TV remote controller will change the points. The sole protection seems to be that the driver normally activates the points from the cab before the tram reaches them. In this case it would seem that they were changed while the tram was passing over them, resulting in derailment. So although the incident (Polish text) may serve as a wakeup call, it does less credit to the ingenuity of the perpetrator than previously thought. However, the problem is not restricted to Poland. Similarly unprotected signalling systems are used for traffic light control in the USA. These have been abused to the extent that a federal law was passed in 2005 to outlaw supply or use remote traffic light controllers.

(mba)