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Why does the Nuvi keep trying to take me on back roads?

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  • Also from baton rouge to shreveport it tries to avoid all interstates. Yep, I have to force it with via points. Are tomtoms different? I can still return mine.
  • Also from baton rouge to shreveport it tries to avoid all interstates. Yep, I have to force it with via points. Are tomtoms different? I can still return mine.
    I certainly would return it and can almost guarantee you will see the routing you expect on a TT. Good luck.
  • SergZak 340 Points
    Also from baton rouge to shreveport it tries to avoid all interstates. Yep, I have to force it with via points. Are tomtoms different? I can still return mine.
    You say you have all avoidances disabled...you should also make sure your Navigation setting is NOT set to "Less Fuel". This sounds like what is happening on your unit. To verify the setting, touch Tools>Settings>Navigation...the Route Preference should be set to "Faster Time" and NOT "Less Fuel". Check this setting on your unit. See page 39 of the Owner's Manual available for download here:

    http://static.garmincdn.com/pumac/3130_OwnersManual.pdf
  • No, its not set to less fuel its set to fastest. I dont think it takes less fuel on backroads with more stops anyway. The navteq website which garmin uses routes the right way. I've tried a route again to shreveport and it statrted giving me the right route on the interstate. It still gives me backroads to south louisiana when the interstate is the best route though.
  • I certainly would return it and can almost guarantee you will see the routing you expect on a TT. Good luck.
    Yes the TomTom does have an edge with its routing but having owned one I can say that the database is not as extensive on the TT. I guess its all in what your priority is for a navigator.
  • lcjhnsn 0 Points
    This thread has now been active for almost 2 years...

    Both my 255 & my 1450 prefer me to travel on commercial & urban streets with traffic lights every 100 feet instead of nearby Freeways. As someone else said, it appears the routing algorithm grossly underestimates the time to traverse surface streets.

    Has there been any comment from Garmin regarding this error?
  • Marc 301 Points
    Last time I asked Garmin about this I got the reply if it gets you there it is doing its job. Call tech support and see if they tell you anything different.
  • BrianL 0 Points
    Has anyone checked the 2012.10 maps for this problem yet?

    We have 2011.40 maps on a 750 and experienced a similar problem this past weekend.
  • mitrajoon 0 Points
    I thought some of you might enjoy the latest escapades of the 265 and was delighted to find a recent post. For those not willing to read through the longest thread in the history of this site, the initial poster asked why his 265 was taking him off main roads on to side roads and then back again. Numerous other posters complained about the same problem, e.g., being taken off a major interstate at one exit and then directed back on to the interstate one or two exits later. My wife and take long road trips once or twice a year and I related my own stories.

    The thread was hijacked a bit by techies arguing about accuracy of arrival times and other digressions but the fundamental problem persists. I have since switched to another brand but I always take my Garmin along for laughs. I plug it in when my wife is driving. Here is the latest.

    We are just completing a 3000+ mile road trip through the South West (Utah & Arizona). On our way to Mexican Hat (because I like the name) we came to an intersection after taking a side trip and the Garmin told us to take a left, fortunately there was a sign saying Mexican Hat was to the right. In fact, the left would have taken us back to Monument Valley.

    Where it would have taken us is a mystery but I think I know the answer because yesterday we were on our way to Kodachrome Basin and it happened again. This time I decided to find out where it would take us as we were only about 9 miles from our destination. So we dutifully went in what we knew was the opposite direction. After 3.5 miles we were told to make a left onto a side road, then a right on the next side road. And again a right. Finally (you’ve figured this out by now) we were directed to make a right on the main road heading back to our starting point. After 3.5 miles we were directed successfully back to the road to Kodachrome Basin. As the poster above mentioned, according to Garmin this is perfectly fine since the unit got us to our destination.

    In case you think this is a Utah thing (which is notorious for GPS issues) I have had the same thing happen (documented above) in Boston, Orlando and Northern California.
  • I am trying out a 2460LMT and I had a Garmin StreetPilot 2610.
    I took a detour off my route by 2 blocks for McDonald's and 20 miles later it had me turn off a 4 lane highway and had me driving down county roads. My route that I laid out on my computer and uploaded to the flash card is still on the GPS.
    Now, at the end of the route, there were 7 way points in 10 miles and it hit all of them just perfect. The new route it chose may have cut off a few miles but it added more time and fuel. PS: I have the 2012 mapset.I downloaded it to my 2460 and my computer at the same time so MapSource could be used to lay out routes.
    Is there any way to turn off the automatic recalculation? I looked at each menu item I could find and had no luck. I think my old 2610 had all types of preferences you could set, including telling it you were driving everything from a motor cycle to a bus. And you could pick if you wanted mostly major or minor roads.
  • Boyd 1985 Points
    If you have spent a few hours using the Nuvi, then you already know everything it can do. There aren't any hidden menus or tricks. Yes, it really is that dumbed-down.

    I also had a StreetPilot 2620 and really miss all the customization and advanced menu's. But those are long gone from Garmin's automotive units. LONG gone.

    If you want advanced functions like that - and more - you can now get them with the new Garmin Montana, but it will be expensive. See this thread: http://forums.gpsreview.net/discussion/22935/x/p1/

    I also posted this the other day. If you can find a cheap 5" tablet running Windows, it might be a good alternative to the current Nuvi offerings: http://forums.gpsreview.net/discussion/23202/x/p1/

    Congratulations... you are now experiencing "Nuvi shock". It's a common disease that afflicts owners of the StreetPilot 2600 series. :D
  • I see why StreetPilot 7200's are selling for $400 or so on EBAY and up to $699 for a refurb unit. I may just buy a 2700 series off EBAY just so I can get new maps. If I could get maps for my 2610 I would not have the 2460.
  • Looks nice but $500-550 and then you have to buy a mapset???
    What's in the Box

    ◦Montana 600
    ◦Lithium-ion battery pack
    ◦USB cable
    ◦AC charger
    ◦Owner's manual on disk
    ◦Quick start manual

    Maps & Software Options

    Click Here for Trail and Topo Maps

    Click Here for Lake and Coastal Charts

    Click Here for Road Maps

    Maps & Memory:
    Basemap: yes
    Ability to add maps: yes
    Built-in memory: 3.5 GB
    Accepts data cards: microSD™ card (not included)
    Waypoints/favorites/locations: 2000
    Routes: 200
    You know, if they would throw in the maps and a remote control, I would pay that. It is less than my 2610 cost in 2003.
  • redvan 0 Points
    Just got a Nuvi 1490 LMT the other day because my Magellan 1470 got stolen.

    Let me say before I go on: I love Garmin, they make great aircraft GPS'.

    However, as this thread is about, routing sucks bad for their land based GPS systems.

    Went to NYC and Long Island this past weekend and wow, I wanted to throw the dumb thing out the window. Get off next exit then get right back on... I cant even count how many times I did that.

    Have it set to "Faster Time", and no avoidances. 2012.10 Maps.

    Having read the first and last pages of this thread, it appears that this routing issue is a major problem, but it sounds like Garmin doesn't agree. I have about 20 days left in which I can return my 1490LMT, so I'm thinking I'll hold off to see if Garmin will do anything about it (doubtful).


    I just sent this following message to Garmin Tech Support. May I suggest everyone else flood them with the same request so that they'll see this really is a problem.

    -------------------------Message to Garmin Tech Support----------------------
    I just got the 1490LMT and used it on a trip to Long Island and NYC. The reason I got this was because my Magellan 1470 got stolen. So, I thought I'd go with Garmin, whom I trust from their products in the aviation world.

    Routing is terrible. The 1490LMT had me getting off expressways simply to get right back on at the next entrance. Multiple times through the duration of my trip to NY. My Magellan 1470 was far superior in routing, and I got it for less than half the price. In my opinion, routing is the #1 thing that should be considered when purchasing a GPS. Garmin does it bad.

    I have the settings set to "Faster Time" and no avoidences. Maps are 2012.10.

    NUVI's NEED a MOST USE OF FREEWAYS OPTION.

    There is no, and I mean ZERO time or fuel savings in getting on and off expressways, or taking back roads (generally). If there were, then Miles Per Gallon as advertised in car sales would display better MPG for city traffic.

    Please add a Most Use of Freeways option in the very near future. I have limited time in which to return my 1490LMT, and would like to keep it, but I cannot keep using a GPS without that option.

    Thank you!
    ---------------------------------END---------------------------------------------
  • JakeBee 0 Points
    Mine started doing the same thing along with the other problems with the 3760T ... even though fastest route was set it start going to back roads. Garmin just notified me that the unit is bad and they are sending a new 3760T.
  • Mine started doing the same thing along with the other problems with the 3760T ... even though fastest route was set it start going to back roads. Garmin just notified me that the unit is bad and they are sending a new 3760T.
    Keep up posted. My new 2460 does the same thing, even though set for faster time. A 268 mile trip took 21 waypoints using Map Source to get it to perfectly follow my route.
  • EWyatt 81 Points
    Just got a Nuvi 1490 LMT the other day because my Magellan 1470 got stolen.

    Let me say before I go on: I love Garmin, they make great aircraft GPS'.

    However, as this thread is about, routing sucks bad for their land based GPS systems.

    -----------------------
    Joining in.... Same here with my new 1450. My destination was .35 miles to my front, and and at the end of an exit ramp just to the right. Instead, the 1450 took me straight ahead .9 miles then circled around some back road to the final destination from the other end. So instead of a .3 mile ride to the destination, it took me around 1.8 miles. Roadway conditions were the same. Preaching to the choir.....
  • Sora000 0 Points
    I have been trolling around the net trying to find an answer to this question and I finally figured it out at least for my nuvi 3790t.

    I have no ecoroute setup and I am asking it to route me with the fastest time. In avoidance make sure to check unpaved roads and traffic, but nothing else. When I check any other option in avoidance the problem begins, and when I uncheck everything the problem begins as well. Just to reiterate: Make sure you check unpaved roads and traffic, and nothing else.

    I am using the nuvi 3790t software version 4.30, firmware version 2.60, and map version 2012.20. I do not know if this will help anyone else, but this is what worked for mine so it might be worth a try.
  • Boyd 1985 Points
    On the 3790 you might also try turning nuRoute off and compare the routing. It can make a big difference. With nuRoute/trafficTrends active my 3790 wants me to take ridiculous routes on little neighborhood streets in Philadelphia instead of the obvious main roads.
  • Sora000 0 Points
    On the 3790 you might also try turning nuRoute off and compare the routing. It can make a big difference. With nuRoute/trafficTrends active my 3790 wants me to take ridiculous routes on little neighborhood streets in Philadelphia instead of the obvious main roads.
    I just tried out your suggestion with my particular configuration and it made the worst route I have ever seen it try haha :lol: So I wouldn't recommend it with the way I have described, but I only have my 1 gps to try this on so maybe it will work for others.
  • Boyd 1985 Points
    I suppose it might have different results depending on where you are. I completely disabled it on my 3790 because it was just trying way too hard to route me off the main roads. With nuRoute turned off, I get routing that is pretty much identical to the other 4 nuvi's I have used.

    But of course, this probably has nothing to do with most of the posts in this thread because nuRoute is only available on the newest models.
  • susanmsusanm 0 Points
    Garmin Nuvi 855 (purchased January 2010)
    Map ver. 2010.40

    I'm sorry to report that my once beloved Garmin that has routed me nearly perfectly for over a year is now all of a sudden doing the weird routing described in this thread.

    It directs me off the interstate, take a little tour of a city, then back on the interstate. Dirt roads are set to be avoided, and yet, Garmin routes me off onto dirt roads that don't even go through to my destination.

    Why would there be a change when I haven't changed any settings?
  • alanb 539 Points
    susanm, I would suggest a hard reset. After the reset, go back through your navigation preferences and avoidances and make sure they are set correctly. The hard reset procedure is described in a sticky http://forums.gpsreview.net/discussion/comment/145946/. Note that the procedure for the 855 is a little different than most nuvi's. If you look down a few posts in the topic linked above, you will find the post by Boyd that explains the procedure on the 800 and 805 series.

    Make sure you back up your current.gpx file before you do the reset. The reset will delete your saved favorites and custom routes, and you can use the current.gpx file to restore them.
  • susanmsusanm 0 Points
    If I don't have any important saved favorites or custom routes, can I skip the back-up step? Or do I need it for any other reason?
  • alanb 539 Points
    Well, a backup is always a good idea, and backing up the current.gpx file only takes a few seconds. You will find it in folder \Garmin\GPX. But if you are sure you don't need any of your favorites or custom routes, yes, you can skip the backup.
  • susanmsusanm 0 Points
    Thanks, alanb. I did a backup of everything right after I received the GPS in early 2010, but I'm not one to save anything in favorites. I know how to get to all of my favorite locations. ha ha!

    I've done the reset so will check out the routing on our next trip. Thanks again.
  • alanb 539 Points
    I should have asked if you are running the latest firmware on your 855. The current version is 4.70. If you are at an earlier version, I would suggest using Web Updater to update firmware. And if you do that, another hard reset after the firmware update is recommended.
  • Just checked and my software version is 4.70. Thanks, alanb. 8) Will post in about a month if the hard reset solved the problem.
  • How do you "turn off " nuRoute?

    All I can do is enable/disable myTrends and trafficTrends, and set the avoidances.
  • Boyd 1985 Points
    myTrends + trafficTrends = nuRoute :)
  • Wonder if the new "guidance 2.0"/"3.0" will help in the new 2012 models?

    I have been using a TomTom for a few months. The routes are generally spot-on though there are certainly more map errors than Garmin has.
  • Same routing problems here on a 2460LMT. Bizarre routing down side streets just to save 0.2 miles in distance. I have Fastest Route checked, no avoidance except traffic and unpaved roads.

    I've tried turning of Nuroute (via the 2 options ).

    The other thing is the Traffic Reporting which really seems to have a mind of it's own. Not the accuracy but the way it responds.

    Sometimes when it's red it will automatically say something like "Traffic Ahead" and re-route me around it.

    Other times it says nothing but will send me around it (I can tell because I am familiar with the roads).

    And still other times it will turn red and won't do anything so I have to hit the "Detour" button and then it will route me a different way.

    I've reset it, have latest firmware and maps and so forth.

    The biggest problem though is the bizarre routing.

    And it happens a lot and in many different locations so I suspect something is wrong with the algorithm it uses rather than the map data.

    It just seems to want to save .2 miles on a 55 mph road by routing me to 30 mph road full of stop lights.

    With all these people complaining of essentially the same, or similar thing, there has to be a problem with the software/firmware.
  • Boyd 1985 Points
    And still other times it will turn red and won't do anything so I have to hit the "Detour" button and then it will route me a different way.
    I don't know about the other issues, but often it will detect traffic but it doesn't think there's any faster way to your destination, so it does nothing.
  • Thanks Boyd!
  • I have talked to Garmin via email regarding this issue multiple times. They simply say that the system uses the speed limit in the system to calculate travel times, and there is no way to adjust the speeds. Thus, here in Southern California, it ignores that arterials with 45 mph speed limits typically average 20 mph, and it takes you on and off freeways that have 2 to 5 minute waits at ramp meters to reenter. The theoretical value here is that the freeways have extensive delays that vary day to day, hour to hour, and sometimes the arterials streets are the fastest way, but the system is only useful in the traffic search mode, but since there are dozens of delays shown, it's near impossible to read. Time to trash the Garmin, and just put my smartphone with Google Maps in it's place on the dashboard.
  • Thanks for this thread. I dropped and broke my 265W yesterday. While I was sorry to have an unexpected expense, I was also glad to have a reason to be rid of the 265W due to the bizarre routing experiences I've had.

    After reading online reviews I ordered a new Garmin 2460LMT. I assumed that the routing issues must have been resolved since none of the reviews I read mentioned them. I do not want another device that takes me off an empty highway, routes me through local streets, and then puts me right back on the same highway at the next entrance. The 2460 will be returned, unopened. (I wish I discovered this thread last night before I ordered it.)

    I can't believe this issue has not been resolved and I find the reported Garmin response (If it gets you there, it's working) infuriating.

    I guess I'll have to look into TomTom and see if their products have any similar issues.
  • susanmsusanm 0 Points
    UPDATE: After performing the hard reset as outlined in the Sticky, I've now been able to test the routing. NO IMPROVEMENT.

    To recap per my 8/31/11 post:

    Garmin Nuvi 855 (purchased January 2010)
    Map ver. 2010.40
    Firmware ver. 4.70

    Routing was perfect for one year, then suddenly went wacko. You know, I could understand if the GPS had weird routing from the beginning. I wouldn't be happy, but I would not be confused. However, to have great routing for a year and then have it start doing this, IS confusing.

    Any other ideas?
  • alanb 539 Points
    @susanm. The only thing I can suggest as a test is to go back through your preferences. Make sure you have the Route Perference set to Faster Time, set all the avoidances (including Custom Avoids) to Dont Avoid, make sure you have the System Usage Mode set to Automobile. And don't forget that on the 8x5 series, you need to do a soft reset after making changes (remove and reinstall the battery)
  • Leopo 0 Points
    My Nuvi keeps trying to take me back roads because it thinks it will be faster but doesn't take into consideration traffic and traffic lights. Is there a way to make it use the hiways instead of back roads?
  • FYI - I finally bought the $20 car dock for my Droid X, and have been using Google Maps Navigation (beta) for free for the past few weeks. It is still buggy, and locks up occasionally, but the routing and time estimation is much better. No more detours onto slow moving arterials. I have to check everyone once in a while whether there is a faster route available, but it actually give me the choice of three different routes with mileage, time and a map showing routing for me to make the decision to divert. At least here is congested Southern California, it has worked much better than the Nuvi ever did.
  • :evil: Grrrrrrrrrrr!

    I recently bought a Garmin 2555LMT (nov 2011) only to have logged more "wrong way" miles on my vehicle by using the Garmin than if I would have used my trusty ole AAA's paper road map, which by the way has never lead me down a wrong road, or had taken me the long way around.

    It "the garmin" keeps trying to rip me from the fastest routes and place me on every back road it can find rather than using the Pennsylvania turnpike, which is the fastest route for my travels from one end the the state to the other.

    Apparently, based by the replies on this forum since 2009 to date, Garmin has been having this problem, regardless of the unit model, and since has yet to remedy it.

    Does Garmin get royalties or kick-backs from businesses, merchants and gas stations by forcing us to use longer more costly and ineffective routes of travel?

    Garmin will be receiving my unit back as soon as I get back to Pittsburgh, Pa.

    I Love You, my trusty ole AAA's paper map! Im sorry i ever doubted your loyalty, devotion or accuracy, and I shall never part from you or cast you aside for some shiny piece of new GPS technology ever again!

    GPS: Gross Possitioning Succubus!
  • You are not alone in this quest. I'm not sure why this isn't discussed more but whatever algorithm Garmin uses for it's routing is hosed. I have the 2465LMT and it does the same thing.
    It will take me off a highway where I am doing 65mph 2 exits before my normal exit, route me down a road full of traffic lights and then onto another road that also has traffic lights and a 30 mph speed limit.

    All to save 0.6 miles.
    Yes I clocked it.

    And it does this CONTINUOUSLY, not just this particular destination.
    I've tried all the options and it has a mind of it's own.
    It goes for shortest distance every time even if it means getting off a highway and getting right back on the next entrance ramp.

    It's totally funky.

    With all the technology built into this thing, can't it figure out I'm going 65 mph, there is no traffic ahead because it's 4AM and the roads it wants to put me on are substantially lower in speed limit?

    My ancient TomTom OneXL which doesn't even speak street names is better at basic routing than this Garmin is.
    Seriously.

    It's hard to believe these things get 4 and 5 star ratings?
    Maybe people are more concerned with the gadgetry than the actual routing?
    I dunno.

    The new TomTom units seem to have a myriad of problems, people either love them or hate them, but routing wise, I can't see how it could be much worse than this.

    Any ideas?
  • After talking to a so called " garmin technician" for an hour and six minutes with no resolve nor compassion from so called technician, I knew right then I was going to return the Garmin 2555LMT as soon as I got home.

    After speaking my disappointment to the BestBuy customer service person she had nerve enough to suggest that I go and pick out another Garmin. Needless to say I declined.

    I will resurrect my AAA's paper map. I do not ever see me considering another GPS anytime soon.

    The end!

    Alexandra
    From Pittsburgh, Pa.
  • I would suggest trying another brand before you go back to AAA
    :D

    They all have their pluses and minuses. One huge plus for the Garmin is the interface. Another is the voice recognition and the way POI are done.
    TomTom's recent units have a difficult to navigate menu structure, but once you learn it , things are easier. TomTom's voice recognition isn't as good and their POI don't show addresses! At least last time I checked.

    Maybe Magellan?

    Never tried one of those.

    I'm pretty certain the routing in all the Garmin's (or TomToms) at the same software level is apt to be the same so that's not an option.

    I just find it odd that what is likely the top GPS, at least in USA, in terms of popularity, doesn't have more complaints about the basic routing scheme?
    To me it's quite bizarre.

    I'm thinking of trying one of the newer TomToms. I don't like the idea of paying for the traffic though. I'd rather have the advertisements.

    I dunno, so many choices :(
  • I just find it odd that what is likely the top GPS, at least in USA, in terms of popularity, doesn't have more complaints about the basic routing scheme?
    Not for nothing is this topic the one with the largest number of views !!

    Garmin really do need to face up to the problem and sort it out as it really is a joke to be told to leave a motorway at one junction - go through a load of side roads with traffic lights etc and then be taken back onto the motorway at the next junction !
    I'm pretty certain the routing in all the Garmin's (or TomToms) at the same software level is apt to be the same so that's not an option.
    Not so, my old TT 730 is much "lower spec" than my Garmin 1490T and the routing is spot on every time !

    What do we have to do to get the message across to Garmin????

    BOB
  • @struttob You know I thought about that 2 seconds after I hit the enter key!
    It is a most viewed isn't it?

    I guess that DOES say something!

    It's funny though, I don't see this on other sites regarding Garmin.
    Maybe I'm just not looking hard enough.

    There is no question that for people most interested in the routing as opposed to all the bells and whistles, this is a big problem.

    I have had this thing route me off a main 2 lane road, onto a side road that more or less runs parallel and then meets up with the main road again 2 miles later.
    I actually drove back and clocked it and it was like 0.3 miles difference, yet I had to drive through a country neighborhood at 20mph rather than the main 45mph or so road.
    It's crazy. That was an unfamiliar place so I figured I'd see if it maybe was me.
    It wasn't.

    It's nice that this thing contains all kind of gadgetry, but seriously folks, why aren't more people upset with the bizarre routing schemes?

    None of these things are perfect, but IMHO this one is consistently poor.

    P.S. Is your older Garmin using the same maps as this new one?
    If so, they changed the algorithm some how and managed to screw it up.
  • @steveo42,
    P.S. Is your older Garmin using the same maps as this new one?
    If so, they changed the algorithm some how and managed to screw it up.
    Sorry by TT 730 I mean TomTom 730 !

    But, I have seen people commenting on how their Garmin units used to be OK but now suffer from the ANTI HIGHWAY syndrome after software updates, so Garmin can do but it seems to be arrogance on their behalf not to want to fix what is obviously a problem of their own making.

    Unfortunately it is only after buying the GPS that you discover the problem, so the only way to get something done is to stop other people buying the units in the first place somehow - Facebook here we come ? - a group for people who want their Garmin to use the motorways and better routing in general.

    BOB
  • @struttob You probably have a point because I have seen this as well and even with the TomTom's people are complaining about the new software in the Go! units not being as good as the older stuff.

    I know my TT OneXL never had oddball routing. It would keep you on highways instead of sending you through some housing development just to save 0.5 miles. Something my Garmin has actually done!

    Where Garmin kills TomTom is in the interface. The new TomTom interface is really poorly designed. Common functions are buried deep in the menus. This is my first Garmin, 2nd GPS, and I give Garmin kudos for a wonderful interface.
    The voice reco also works very well.
    With TomTom you have to hit an icon on the screen to start Voice reco. Kind of self defeating I think.
    Also the audio on Garmin is excellent. Very loud, even in my Mustang GT with the top down I can hear it.

    Honestly, the only thing I really hate about my Garmin is the routing which I guess is kind of important to me 8)

    I'm gonna call tech support next week after the shopping weekend quiets down and see what they say. I suggest the other ~ 690 people in this thread do the same thing! hahahah!
  • @steveo42

    A flashy interface is fine and with the routing given you have plenty of time to look at it :wink: To be honest the only thing I prefer about the Garmin over my old TomTom is the big screen, you get used to the interface in about 5 minutes.

    I thought the primary function of any GPS is to get you where you want to go in the way you want (fastest route in my case) and this the Garmin fails to do a good job at.

    I would suggest that if all 690 people ring tech support you will have NO chance to get through, it is difficult enough at the best of times !!

    BOB
  • The causes of these nuvi flaws are pretty obvious and are essentially map data errors / limitations.


    Glitches like a right turn where a left was expected, followed by a left, right, right, right (which puts you back on course) are caused by faulty data (like an incorrect left turn prohibition, for example, but more likely a "the road segments just don't connect that way" linkage error)


    The "highway avoidance" is caused by incorrect speed limit values that are based on road classifications, combined with the nuvis' total disregard for stop signs, traffic lights and urban congestion.

    I'm using the latest CN NA 2012.30 map up here in Canada on a 255W and 1350 and have observed the following:

    - the nuvis think that the speed limits on our 100 kph expressways (like the 400 series) are 100 kph

    - for our 80 kph highways (e.g. most of the roads in the boonies), the nuvis think they're all 90 kph routes

    - 60 kph city streets are all 70 kph streets in the nuvis' eyes

    - for many of the 50 kph city streets, the nuvis think they're 70!

    - 40 kph and lower residential roads are all 50 kph to nuvis

    So whenever you have an expressway route that bends, the nuvis think that the straight route on "70 kph" roads is faster than the longer 100 kph expressway. Of course, the reality is that the straight route has a 50 or 60 kph speed limit and is peppered with red lights and congestion. The combination of errors (bad speed limits, invisible stop signs / stop lights) makes the nuvis grossly underestimate the time required to navigate non-expressway routes.

    The estimates are so bad that here in Toronto, the nuvis think that a trip from St. Clair Ave down Avenue Rd to Bloor and then east to Yonge St (a 2.7 km crawl on 50 kph roads that are littered with traffic lights) is a 70 kph non-stop blast that takes only 2.3 minutes. The reality is more like 5 to 15+ minutes.


    The "get off the highway only to get right back on" behavior (see bill_sc's screen shots on page 12) are caused by errors in the highway data; the nuvis see a short borked section with a major speed drop and figure that breezing down the offramp, blowing through the invisible stop sign / traffic light and then going up the onramp is faster than slowing down to a crawl on the highway at the borked bit and then re-accelerating. Veering through a rest stop - same problem.

    Computer generated maps are full of stuff like that and it takes forever for vendors to fix all of them. Typically, if you don't report it, they'll never fix it.


    As for the major problem (highway avoidance), Garmin got themselves into this mess by using map data that doesn't include accurate speed limits, stop signs, traffic lights, etc. and then not dealing with these data limitations in their firmware. TomTom did the right thing by augmenting this crappy data with real world data collected by their customers.

    Garmin seems to be sitting on their butts, waiting for the map data to improve - speed limit data is slowly being added, but far too slowly to solve this problem. They really should have done themselves a huge favor and added some better options a couple of years ago, perhaps along these lines:

    - Avoid (most) non-highway roads (e.g. pick the route that uses the fewest surface routes)

    - Penalize <roadType> by <x> percent (e.g. penalize city streets by 100% - if the nuvi normally thinks a route through town will take 30 minutes, derate it to 60 minutes; by tweaking <x> to match your city's actual traffic woes, you could get your nuvi to actually work...)

    Garmin knows exactly what the problems are, but instead of addressing them in some useful manner, they've just been stonewalling their paying customers.
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