Street sign theft

Street sign theft occurs when street signs are stolen, to be used as decorations, sold as scrap metal or to avoid obeying the law by claiming later the sign was not there. Although the theft often seems arbitrary, signs with unusual or amusing names tend to be stolen more frequently. Sometimes considered to be a prank by the perpetrators, the theft is often costly and inconvenient (and can possibly be dangerous) for the municipality or agency that owns the sign. In the United States, each street sign generally costs between $100 and $500 to replace.
In law.
In most jurisdictions, the theft of traffic signage is treated like any other theft with respect to prosecution and sentencing. If, however, the theft leads to an injury, then the thieves may be found criminally liable for the injury as well, provided that an injury of that sort was a foreseeable consequence of such a theft. In one notable United States case, three people were found guilty of manslaughter for stealing a stop sign and thereby causing a deadly collision. This was publicized in the novel "Driver's Ed" by Caroline B. Cooney.
Prevention.
Some jurisdictions place stickers on street signs warning of the legal punishment for their theft. Some cities (e.g. Toronto) use specially designed bolts to attach signs and prevent removal.
With some of the more popular street names such as Liverpool's famous "Penny Lane", authorities gave up the practice of constantly replacing signs and simply resorted to painting the name of the street on the walls. Other jurisdictions offer replica street signs for sale to discourage theft. For route markers or mile markers that contain numbers with suggestive meanings, such as 69, 420, or 666, the number may be changed to avoid sign theft.