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I'd like to know how GPS can determine if a street is one-way. Does it detect one-way signs or parked car positions if any?

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    No. A GPS itself only detects the geographic location of the receiver. Assuming that you're referring to GPS units for cars (e.g., TomTom), the unit cross references the location with an existing database of road names and attributes. – Christopher May 11 '14 at 1:43
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    Yes, the one-wayedness of the street is stored in the routing data depending on the type of unit. One such dataset I had access to duplicated the roads: one for one way, the other for the reverse. The program only traversed roads from start to end and not end to start so a one way street was simply not duplicated. There are other ways to solve this problem but it depends on the software. – Michael Stimson May 11 '14 at 1:57
  • OpenStreetMap tags can help understand the underlying data and one ways wiki.openstreetmap.org/wiki/Key:oneway#Translation_for_routing – Mapperz May 11 '14 at 1:58
  • @ChrisW Thanks. Never sure whether to post quick answers as answers or comments. – Christopher May 11 '14 at 19:26
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    @Christopher If it's a true answer, always as an answer no matter how short. If it's a hypothetical answer where you're not quite sure if you understood the question or whether they tried something already, comment that you convert to an answer once they confirm you were on the right track. – Chris W May 12 '14 at 18:58
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No. A GPS itself only detects the geographic location of the receiver. Assuming that you're referring to GPS units for cars (e.g., TomTom), the unit cross references the location with an existing database of road names and attributes.

  • Yes, I'm referring to GPS units for cars. Can you provide some more information on these databases or point me toward some resources? I see cars driving around with cameras on top which I think are for street view on Google Maps, do those drivers feed road names and attributes into the databases? – asdf May 12 '14 at 23:19
  • @Borracha Some GPS manufacturers may assemble and maintain their own streets databases, but more often they purchase it from companies who offer that as a primary service (such as NavTeq, now known as HERE). Street view cars you see are generally only collecting imagery. The companies that do it may also produce street databases or purchase the data from elsewhere. Street data production is typically done through collecting and incorporating records from local municipalities or digitizing from overhead imagery. Driving roads just to collect and attribute data is not very efficient. – Chris W May 13 '14 at 1:05
  • @ChrisW That pretty much answers my question. Thanks – asdf May 14 '14 at 3:42

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