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  • Latitude

Garmin GPS makes some “interesting” routing choices

Posted by Jeff on July 15, 2008

I’ve seen this too many times for it to be a fluke with one device or even model. The Garmin mobile gps devices make some insane decisions for routing from one place to another and I can’t decide whether it’s due to poor maps or a poor routing algorithm. Our family uses the StreetPilot c550 and HVA uses the nuvi series, and I’ve seen the same issue with both.

A good example is our most recent trip to Cleveland from Milan. A reasonable person (and Google) would take US23 south to either I80/90 or I475 to get to the turnpike. Our garmin directed us to get off US23 at Summerfield, take that to Sterns, to Lewis, to I-75, to I-280, and thence to the turnpike. For those not in the know, these are all two lane back roads and while possibly more direct, it would be MUCH slower than staying on the highway.
On our first trip to Cleveland, we had to pull into a residential street to get out the laptop and look up directions online, since our Garmin kept taking us around in circles AROUND our destination, without actually taking us TO our destination.

I’ve seen the same thing happen with the nuvi series, where crews have followed the gps onto rural, 2-lane roads that end up being more direct but much slower, or have gotten stuck in the loop-around route.

I’ve triple-checked the settings in several of the units and they are all clearly set to choose the fastest route with all obstacle avoidance turned off. The weird thing is that our StreetPilot has actually tried to route us a couple ways around Toledo on several different trips to Cleveland, with the same start and end points, and all settings the same.

I am curious if I would experience the same bugs with another manufacturer (TomTom, maybe), or if it is a deficiency in a shared routing algorithm.

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4 Responses to “Garmin GPS makes some “interesting” routing choices”

  1. uncle jimmy said

    My Tomtom One xl does the same but not as bad as you describe. Sometimes a “renavigate” helps, sometimes not. But it always gets me there, if not elegantly. (Or close – street addresses are supposed to be logical but there are oddities in that system, too.)I think it’s mostly map data (with NAVTEQ and TELE ATLAS being the big 2 suppliers). GIGO (garbage in/out) or NIGO (nothing in garbage out.) I’m not sure if the adjunct street data is really complete. Things like timed stop lights (fast in one direction – slow in the other) ; malfunction junction info “..takes 3 light changes to make a left turn at THAT intersection..”; bad neighborhoods (important in Detroit), etc. I was getting good local routing with the original OS and map. Then I updated both (free since the competition is hot)and found the routings a little LESS obvious! Typical ‘upgrade’. Tomtom lets you make corrections (dead ends; long term road destruction, etc. and store on your unit (not easily, though.) But if you already know about the change who needs a GPS? However, you can then upload the changes you make to their server. I assume they check validity, and then they allow all users to download the map changes. Tomtom also has a deal with Google to interact with Google maps. They also ask your permission, when you connect to their server, to access recent trip data stored on your unit to get actual routes and times/speeds. Scary, but useful info to them. I think I’ll drive to all the strip clubs, bars, and dope houses in the area, submit that data, and wait and see what shows up at the front door or in the mail!!
    It’s fascinating now ( I remember working with just one GPS satellite a while back!) and should get better.
    CU, Jimmy

  2. Kathie said

    Driving back from Seattle (the long way making stops in Glacier, Yellowstone Grand Teton and Badlands National Parks) we had the final segment going through Chicago. The GPS (I believe Garmin) decided that it was wise for us to exit, continue about 500 feet (directly along side the tollway we were on) to the next entrance back on the tollway. Not only did we loose the time of slowing down to exit and drive on the service drive but we also got to pay the Toll a second time. Yippee! =( I think we all feel your pain when driving by GPS!

  3. Michael said

    I think I may know exactly which intersection Kathie is referring to. I know that when I’m driving beyond O’Hare airport westbound on freeway 90 toward Rockford, the Garmin Nuvi suggests that you exit at freeway 355/highway 53. Nuvi suggests to remain in the left lane, which puts you right back on 90 toward Rockford. All along (for about a mile), you’re just riding alongside the main freeway 90 artery.

    Lesson: You have to occasionally take the Garmin Nuvi directions with a grain of salt.

  4. Mark said

    A salesperson at Radio Shack said the nuvi calculates trip time on the assumption that you will never be stopped at a traffic light (that you can travel the distance at posted speed).

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