nuvi Route Accuracy
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 17 years
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I am loosing confidence in my nuvi 350 lately. I was traveling south in Texas and checked the route I wanted in Mapquest and Microsoft Streets and Trips. Sitting at home I checked the route on the GPS and it was the same so I was good to go. When I started out the GPS had a new route that was longer and made no sense except it had a longer distance on interstate. After many attempts to get me to go back to her route she finally agreed to go my way. She is really persistent. Later in the trip I changed the preference from fastest to shortest distance to see if that worked any better but it still chose the wrong route. In Texas there are a lot of state and county roads that have 70+ speed limits with little traffic so they are faster even slowing down for towns. All the roads are in the database and once it follows the route the ETA is about right if you go the speed limit so I think they have the correct speed limit in the database. I can't figure out why the routing is less than optimum. Has anyone else seen this problem?
The map
The map doesn't always have the same speeds associated with a road that exist in real life. The maps often go by road "types" rather than by specifics, and that can cause some less favorable routes at times. Here in the Denver area, the map identifies two roads the same, but one has been upgraded for fewer access points and fewer stoplights, thus is MUCH faster to drive than the other one. But since both look the same to Jill (3 lanes each way), she will always try and route me on the most direct street from my current location. Since I know better, I just ignore her protestations and pretty soon she sees it my way.
The road system is so complex that I'm usually amazed when she does find the right route 95% of the time.
Rick - Nüvi 260 - eTrex Summit HC
NUVI 750 - 2009 map I have
NUVI 750 - 2009 map
I have found that I can only use the Nuvi as a general guide. The Nuvi does not distinguish between main routes or side streets if its 2 lane (one direction. It will guide you through what it thinks is the fastest route/shortest route. This can take you down a street with lots of stop signs and crossing main routes. This is a major flaw IMO in map information. The unit is only good for showing you a way to get to your target. I haven't tested the one way street accuracy yet but that can also be an issue in a strange city. The best way to use these units is to #1 enter your destination #2 get the Nuvi to calculate the route #3 zoom out to see general location and route and 4# pick main rout to travel on. Nuvi will re-calculate a few times but you will get there. It would be interesting to find out if the TOM TOM's or other units are better!
The grass is not greener
.... It would be interesting to find out if the TOM TOM's or other units are better!
If you read the reviews on GPSmagazine.com, they have performed several side-by-side comparison tests of the routing engine efficiency. It was really interesting to see 3 different GPS units pick significantly different routes. Garmin was consistently the best routing engine, based on time and distance. So the bottom line verdict is that they will ALL do some wacky things. I found this review section below that compares routing differences between a Garmin, TomTom and Magellan to be an interesting read:
http://www.gpsmagazine.com/2008/02/garmin_nuvi_750_review.ph...
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Here's another comparison with TomTom's new IQ routing:
http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=110142...
Depending where you live, TeleAtlas can be more up-to-date than Navteq and Vise versa.
Learn something every day!
Learn something every day! It is understandable that the route may not be as we would normally drive when you consider all the information that has to be put into a database for every city, town and country road. The file would be enormous and impossible to maintain. They are great units never the less! Especially for people like me who can get lost going around the block!
GPSr Accuracy
want to understand your GPSr Accuracy? Check out this link.
http://www.romdas.com/technical/gps/gps-acc.htm
Bob
Using Android Based GPS.The above post and my sig reflects my own opinions, expressed for the purpose of informing or inspiring, not commanding. Naturally, you are free to reject or embrace whatever you read.