Lye is a is caustic substance once used to make soap, and nowadays it appears in oven cleaner, chocolate etc. So it's conceivable that there would be many streets around the english-speaking world called Lye Close. There may well be- the UK google maps site lists a single Lye Lane in St Albans, and UK Multimap shows 25 road names with "Lye" in the title- but no Lye Close or Lye Street.
Turning to the printed edition of the Bristol A to Z map, off Canynge Square, we find a Lye Close. Perhaps the only one in the country. It's not even in the index. If you visit Canynge Street, you'll find a pleasant, leafy Georgian-looking street, without a Lye Close anywhere to be seen.
That's because Lye Close is a Trap Street.
Trap streets are deliberately added to maps as a kind of watermark. If an organisation copies a map that you have painstakingly charted, drawn and kept up-to-date; they could argue that they'd also done the required theodolite-squinting and trundle wheel-rolling to come up with their own map. But if their map has a street that isn't there; and the only possible source for that street is your map... then you'll be able to show that they've ripped you off.
Why "Lye Close"? Well, I suppose it's considered witty by its instigators since it sounds like a night-time instruction. And it contains a homophone for "lie".
Other examples of Trap Streets are Moat Lane and Torrington Place in London N3; these are on google maps, but not in the real world. The snazzy 3-D Globalvision "Above Ground" maps on the Piccadilly Line get the (unlabelled) area around Greyhound Road, W14 completely wrong. Patrick's Hill cannot be found in Cork, except on the map. The A to Z Street Atlas Company has says there are about 100 trap streets in London alone - about one per page!.
Several court cases have hung on the existence of trap streets and similar features. Most notably, in 1999, the UK's Automobile Association was caught copying Ordinance Survey maps without permission.
Dictionaries make similar entries in order to prove at some later date that the new kid on the lexicography block is a copycat. Even Aleister Crowley is said to have put fake occult knowledge (whatever that would mean) in his books, in order to catch out the unwary.
- Google Maps: Moat Lane
- Google Maps: Torrington Place