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

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Comments

  • aslg 0 Points
    Are you sure you are not confusing cause with effect?
    cause->effect: I have a problem, I look around for solutions to my problem
    effect->cause: Everything is going too well for me today, let me look around for problems I could have :)
  • gatorguy 326 Points
    edited February 2010
    Nope. Similar to an advertisement. Ever think you need something you didn't know you needed? Happens to me with every Sunday's sale ad from Best Buy. :)
  • The issues have been well documented.
  • gatorguy 326 Points
    Dequardo, yes, there appears to be some valid question marks on the xx5 routing on certain specific routes. But getting to "well-documented" has been a problem. There are many routes mentioned in this thread where no issue may really exist. At least two frequently mentioned specific routes differ in their ETA by one or two minutes, even according to IQR on a TomTom. Moving the finish by two blocks on one with several comments changes the route to one the OP thinks is the fastest in their opinion. At least some others couldn't be duplicated. Some turned out to be user error/confusion with "Shortest" vs "Fastest". Truly bonafide head-scratcher routes? Perhaps a half dozen or less out of several pages. If it takes you off an interstate to only be routed right back on, and routing is verified to be set to fastest, then that's an oddity I'd agree is incorrect and Garmin needs to check out the cause. (I suspect at least some of those to actually be set for "shortest".) But trying to get validated, checked results with route specifics has been like pulling hen's teeth. Either the posters never post back to verify their settings, or the alternate routes are never driven to confirm estimated travel times don't agree with real results, or the posted route complaints are so vague that we can't enter them to duplicate. More often than not the poster just "knows" the fastest way can't be the one his/her Garmin picked. Several pages back I requested verifiable problem route specifics to attempt to find some pattern. I think I got one.

    The number of unique posters with at least vaguely detailed route complaints in this thread is actually fairly small, but certainly vocal.
  • Tim 1480 Points
    Then there are also the cases where a hard reset on the device actually changed the routing to become more favorable again for some people.
  • gatorguy 326 Points
    Yup. Forgot that one too.
  • aslg 0 Points
    Nope. Similar to an advertisement. Ever think you need something you didn't know you needed? Happens to me with every Sunday's sale ad from Best Buy. :)
    Here we are talking about problems not stuff to buy. They lead to two completely different Modus Operandi.
  • aslg 0 Points
    Then there are also the cases where a hard reset on the device actually changed the routing to become more favorable again for some people.
    Does this happen for real? I remember there were discordant views on this.
  • SergZak 340 Points
    edited February 2010
    In my personal testing, I believe it does. The nuvi seems to record, store and then use your average driving speed when calculating routes. This can be clearly seen by hard resetting the unit, then set up and run a simulated route (with GPS simulation on). Note the maximum road speeds used in the simulation.

    Now use the unit for a couple of days or so and rerun the same simulation and note the road speeds used...they will now likely be closer to your average driving speed.

    Now hard reset the unit again and the road speeds used in the simulation will be back to the default according to road classification.

    See the following article:
    http://www.gpsreview.net/train-your-nuvi-eta/
  • gatorguy 326 Points
    Nope. Similar to an advertisement. Ever think you need something you didn't know you needed? Happens to me with every Sunday's sale ad from Best Buy. :)


    Here we are talking about
    problems not stuff to buy. They lead to two completely different Modus Operandi.
    Gotcha :roll: Yeah, nothing at all similar.

    Thanks for mentioning the reset Tim. I forget now who stumbled on that. That would help explain at least a few that claimed all was good until they updated maps or application.
  • Tim 1480 Points
    Does this happen for real? I remember there were discordant views on this.
    One example was in the Returning my 855 thread.
  • This driving behaviour is absolutely recorded by the nuvi.

    I have purposely ensured that I haven't made a master reset for the last couple of months and have recorded the eta's on several routes I drive regularly.

    One such route of 79 miles after master reset gave an ETA of 1hr 26mins, after 2 months of driving it is now recording a time of 1hr 38mins, so this is a big difference. The actual driving time for the route is generally 1hr 50 to 55mins, so is still some way off accurate, but much better than post hard reset.

    It hasn't at any point changed the route I may add.

    Maps used are CN Europe 2010.20 and the most recent journey on .30, though this was checked as being the same driving time before the journey.

    As discussed elsewhere, if Garmin employ Navteq traffic patterns any time soon it will no doubt throw all of these issues up in the air. No hard evidence that this is actually planned as yet however.
  • You would think, in this age of do-it-yourself blogging and this website and others, there would be some sort of documentation or visual proof of what is going on.

    I mean, if it is an inherent flaw in the routing software of certain models, it would be reproducible. If it is reproducible, it would be easily slapped up on a website for all to see.
  • Tim 1480 Points
    Unfortunately, we've been high on chat volume and low on people giving firm examples. We've had a few people come forth and give examples, but far fewer than you might imagine based on the number of posts in this thread.

    I'd be happy to host a google map to share your examples. I believe I've set it up so that anyone who has the link can edit the map. (Although I haven't tested with another account.)

    Make the route as short as possible where the Nuvi still takes the bad route. Use your username here as the name of the route so we know what's what. After creating the route, you can remove the starting and ending point and just keep the line that represents the route to reduce clutter. (I'll trim them out if I find them or if you can't figure out how.) It would also be helpful to know the model, firmware version, and map version in the long description.
  • So I routed a map to a friends house (I live on the northside of Chicago, he lives in Plainfield IL) The 255w routed me through all side streets started from Sheridan Rd. about 7600N (for obvious reasons I did not state the exact location and addresses but it shows that the 255w routes incorrectly.) I have the Nuvi 255w set on "shortest" distance and avoidance set on the following: NO U TURNS, TRAFFIC, FERRIES,UNPAVED ROADS.
    Here is the route Garmin took me on:
    L. ON N. ROGERS AVE.
    L. WESTERN AVE
    RIGHT ON OGDEN
    L. PLAINFIELD RD.
    L. EAST AVE. (21M)
    RIGHT ON PLAINFIELD RD.
    L. LEMONT RD. (30M)RIGHT ON 87TH
    L. NAPERVILLE RD.
    R. 127TH
    L. KENSINGTON
    L. NORWICH
    R. NOTTINGHAM
    Only a crazy person would follow this route (if you didn't know the area, which the point of all this). I would've taken the LSD (lake Shore Dr.) to the 55.
    I tried the same route using Yahoo maps, sure enough Yahoo took me on the most direct route, LSD to 55. So how is this possible? Garmin the most popular gps unit for consumers mess this up? It continues to route me through side streets, painfully frustrating.
    I also tried both shortest and fastest route program.
  • alanb 539 Points
    I would suggest changing the navigation setting from "Shorter Distance" to "Faster Time". "Fastest" almost always gives a better route than "shortest".
  • gatorguy 326 Points
    This is another example of misunderstanding routing choices. As Tim already mentioned, the type of route you posted using "Shortest" would not be unusual. It did exactly what you requested. It attempted to compute the shortest mileage for your route, regardless of speed limits, number of turns, or travel thru local and/or highly congested streets. Strictly speaking, using local roads can often be the shortest distance, but golly, those slower speeds can really add time to your trip and probably not the best way to get where you're going in most cases. Unless you're looking for a casual Sunday drive, or just wanting to enjoy the scenery, I can't really think of too many other times I'd want to use Shortest rather than Fastest routing.
  • kenp 92 Points
    How strictly does a Nuvi adhere to the specified avoidances?

    I have "no u-turns" specified, but it will still tell me to make a u-turn if I go off-route and has not yet accepted my decision. Also (as a specific instance) when navigating to a McDonalds in the POI list (Rte 24, Edgewood, MD, I-95 Exit 77) it told me to go past the place and make a u-turn. Even odder, there wasn't even a need to make a u-turn - there's a left turn lane that's been there for years.

    Ken
  • Ric01 0 Points
    I would suggest changing the navigation setting from "Shorter Distance" to "Faster Time". "Fastest" almost always gives a better route than "shortest".
    I concur with this thought. When I was traveling south along I-5 from Vancouver to Seattle, my 775T keep wanting me to turn off the highway to smaller roads in Washington state and Seattle was still more than 2 hours south. I realized that my unit was on "shortest route" setting and as gatorguy pointed out, the GPS algorithm calculated that taking the smaller roads south would be the shortest route but it will take me 4 hours if I stick to the small roads. After changing the setting to "fastest route", my GPS kept me along I-5 all the way.
  • This may be already tried, but has anyone tried running the routes online to see the routing choices?

    I guess the arguement could be made that Garmin uses its own routing engine, and that's not necessarily the engine that Navteq uses?

    Well, since I am here, I ran the test, routing from Key West, north to Knoxville. The Navteq website doesn't show any odd detours like previously reported.

    Also, TomTom has their routing choices online too. Pretty cool to see both options.

    Navteq:
    http://www.navteq.com/

    TomTom:
    http://www.routes.tomtom.com/t/#/

    (Also, an interesting observation: The default setting is "fastest route". you can change it to "shortest route" and the routing becomes much different)

    ETA: Another interesting observation. I checked the routing from my house to the Sommet Center in Nashville, TN (site of the SEC Championship), and the TomTom has a much faster estimated drive time, when comparing the same routes. This hinders the theorey that Garmin underestimates driving time, right? On a side note, Garmin's fastest route routes me a different way than I normally go, saying it is 10 mins. faster than my normal route. Interesting
  • kenp 92 Points
    I've plotted the same trip on my Nuvi and Navteq's web site, and also on Mapquest and Google Maps.

    Mapquest and Google Maps usually give the same route, turn-by-turn identical. Estimated drive times differ by surprising amounts. In one case, one of them gave 3 hours, the other 3 1/2 hours for identical turn-by-turn routes.

    The Nuvi and Navteq often give different routing from the other sites, and often different from each other. On a route from Northern Virginia to Brooklyn, NY, both routed across Manhattan (vs across Staten Island for the others) but used different bridges from Manhattan to Brooklyn. The Nuvi's choice made a lot more sense.

    Ken
  • Tim, I have two examples of bad routing to show withing city limits. Was able to edit the existing map-not sure how to save it and not sure where to list firmware data, etc.
  • That must be the Corpus Christi route mentioned several pages back?
    I was recreating the trip mitrajoon (from the first page) took from Key West to Atlanta, and it gave him a funny detour off in Orlando.
  • gatorguy 326 Points
    Thanks for referencing back to that first page. :)

    Early on one member had mentioned that a hard reset of his nuvi after the map update made his odd routing go away. Honestly never remember seeing that at the time. When someone (in Dec?) mentioned that a reset of his 855 corrected things, I thought that was new info. I guess not.
  • device: Nuvi 200
    maps: North America '09
    settings: only avoidance checked is 'unpaved roads,' same results with 'faster time' or 'shorter distance'

    Just read through a bit of this thread and decided to do a quick test with my Nuvi. It failed.
    Going from my house to work, the Nuvi always takes the longer route to get onto the highway (longer time and distance)(after getting onto the highway, it does fine). To get onto the highway from my house, I can either drive north from my house several miles and catch an onramp that is north of my house, or I can drive south from my house for several miles and catch an onramp that is south of my house.
    To get to work, I need to go south on the highway and driving to the southern onramp saves about 6 miles and several minutes, instead of driving to the northern onramp.
    Even though the Nuvi's calculations are off (it tells me that using the southern onramp will save 2 miles and 1 minute), it does agree that using the southern onramp is shorter in distance and time. Yet it still always wants to send me up to the northern onramp.
    Here is what the Nuvi is calculating to get to work:
    Nuvi's quickest route, sending me north: 17miles, 22min.
    If I force Nuvi to go south with a via point: 15miles, 21min.
    Granted, the Nuvi thinks it's only 1 minute quicker going my way, but it should pick the quickest route if that's what I want.
  • I just tried the same trip with Google maps.
    Google maps sends me the same longer route as the Nuvi does.
    But when I force the Google map to go my way, it adds 1 minute to the trip instead of shortening it by 1 minute as the Nuvi does.
    The time difference between the Nuvi and the Google might be because the Nuvi has learned the speeds that I drive on those roads, so it would be a bit more accurate (or realistic) than the Google.
  • Tim 1480 Points
    edited February 2010
    The time difference between the Nuvi and the Google might be because the Nuvi has learned the speeds that I drive on those roads, so it would be a bit more accurate (or realistic) than the Google.
    That doesn't go along with all of our other testing to date which suggests that the Garmin "learning" function applies only to the final ETA that it displays and not the route calculation itself.
  • Tim,
    1st: you talk about the 'google learning function,' but did you mean the 'Garmin learning function?' I don't see how the google can learn since it doesn't know how I drive.

    2nd: (if you were talking about the Garmin learning function..) you say that the learning function applies only to the final ETA displayed, not the route calculation.... But, before you actually start moving, wouldn't the 'final ETA displayed' get it's info from the route calculation. I mean, if the route calculation tells me the route should take 15 minutes, doesn't the 'final ETA displayed' use that info to figure what time I should get there.
    Or have I totally missed whatever point you were trying to make? Sorry, it's still early in the morning for me.
  • Tim 1480 Points
    1) Yes, Garmin.

    2) Yes, but no. :) Our testing has shown that the route gets calculated based on the road classifications written into the default map database. After that, the estimated time is adjusted based on the driving profile. So in theory when comparing route A and B, if route A is faster based on the default map database but route B is faster when the driver profile is applied, the GPS will route on route A, but adjust the ETA accordingly, even if the ETA is then longer than the adjusted time would have been for route B. That is what our testing has shown anyway.
  • gatorguy 326 Points
    Which would explain why forcing a route may sometimes give you a better ETA even tho "fastest" was requested. Going by the map data, your forced route may not be faster. Accounting for your driving habits, it is.

    Along those lines, I have no idea why Garmin has never taken that next logical step and applied your stored trip stats to the route computation itself.
  • Tim 1480 Points
    Which would explain why forcing a route may sometimes give you a better ETA even tho "fastest" was requested.
    And another reason is explained here: When is the fastest route not the fastest?
  • Good reading.
    Thanks fellas.
  • I use my GPS for areas for which I am unfamiliar. I know the GPS will get me to the destination. It may not be the best route, but it will work. I see no need to use the GPS for routes to work or for within an area I know. My brain and decision power is much superior to the GPS in a familiar area.

    So why be concerned about GPS routing issues? If you know a better way, take it. Otherwise trust the GPS to get you to your destination, if not optimally, at least accurately.
  • cuc tu 91 Points
    Which would explain why forcing a route may sometimes give you a better ETA even tho "fastest" was requested. Going by the map data, your forced route may not be faster. Accounting for your driving habits, it is.

    Along those lines, I have no idea why Garmin has never taken that next logical step and applied your stored trip stats to the route computation itself.
    Isn't it all relative?

    Nuvi calculates a route based on emperical road data, it then displays an eta, or time to arrival, which is based on what it's learned about my driving habits.

    If I then force my route and the eta is sooner, it is still based on my driving habits.
  • gatorguy 326 Points
    The difference is that it doesn't calculate a route using your personal driving data. Thus the ETA is based on driving history but the computed route is not. So even tho the map data may indicate your forced route would be slower, your ETA may not be since it's coming from your personal history
  • gatorguy 326 Points
    I thought I should mention something just so it's clear. The ETA your nuvi displays is based on your personal driving history AFAIK. It's not displaying ETA based on just the map data itself. So the travel speeds over various road classes and the ETA based on personal data may not work in lockstep. It's very possible for the map data to indicate a certain route may take 50 minutes, but for your ETA to show as 45. There's a couple of ways I can think of to get the raw unadjusted ETA. Either via a Navteq-based planning site like MapQuest or Map24 (at least I think those are unadjusted) or doing a hard reset just before computing a route so that no driving history exists. That's how I understand it anyway.
  • Tim 1480 Points
    I'm not sure it is safe to look at any Navteq based website to see the ETA of a particular route and know that it is also the Nuvi ETA. While they should be looking at similar data, they might use their own speed estimates for certain road classifications, estimate different time amounts through intersections, assume different acceleration/deceleration rates, etc. I think a hard reset is the only way to go if you want to see ETAs without the learned data.
  • gatorguy 326 Points
    Thanks once again for clearing up the details Tim :)
  • Tim 1480 Points
    I probably could have put it more clearly... for the same reason that two GPS devices with the same map data/version (like Garmin/Magellan) sometimes produce different routes, the ETA between applications interpreting the same data can vary.
  • cuc tu 91 Points
    I just tried the same trip with Google maps.
    Google maps sends me the same longer route as the Nuvi does.
    But when I force the Google map to go my way, it adds 1 minute to the trip instead of shortening it by 1 minute as the Nuvi does.
    The time difference between the Nuvi and the Google might be because the Nuvi has learned the speeds that I drive on those roads, so it would be a bit more accurate (or realistic) than the Google.
    My point is that:

    Google shows the forced route as slower. This is a "road data" to "road data" comparison.

    Nuvi shows the forced route as faster. This is a "user data" to "user data" comparison.

    The question is obviously rhetorical, but why?

    You would also question why does the forced route on the Nuvi show as faster than the unforced route, when both route ETAs take into account your driving habits, unless there is some odd idiosyncrasy that has been recorded for either of the two routes such as a particular road type that is either very quick or slow.
  • gatorguy 326 Points
    In a nutshell: Your nuvi computed it's "fastest route" using map data. It then displayed the ETA after adjusting for your personal, stored trip data. No matter what your adjusted ETA is, it is not considered at all in the route computation. They are separate and distinct.
  • I use my GPS for areas for which I am unfamiliar. I know the GPS will get me to the destination. It may not be the best route, but it will work. I see no need to use the GPS for routes to work or for within an area I know. My brain and decision power is much superior to the GPS in a familiar area.

    So why be concerned about GPS routing issues? If you know a better way, take it. Otherwise trust the GPS to get you to your destination, if not optimally, at least accurately.
    I know it seems like I'm lurking here, but this discussion is interesting and has answered some questions about why the chosen routes are not always the "best" in my opinion. Thanks to all you smart, involved folks who have taken the time to explore why these things occur!

    But regarding why someone would use their GPS for known routes/destinations, one word sums it up for me - traffic.

    Sure, I know my way all around town and to most major cities in my travel area, but I always program in my destination. (unless I'mgoing to the store or something!). Traffic updates have literally saved me hours of "stuck" time by alerting and rerouting.

    Of course, if your unit doesn't have traffic, well, then this is meaningless! But with current trends, I can't imagine having a modern GPS without it.

    One final question - to add to what Darrengsaw said, does the Nuvi take into account stop signs and stop lights? If the routing only considers distance and speed limit, lights and stop signs can make a considerable difference! Depending on the complexity of the intersection, some lights can take 3 minutes or more. 3 of them on even a short route (if you hit all red) can add a quick 10 minutes to your trip!
    I would add that unless stop signs and lights are considered, "Fastest" may or may not be "Shortest" but might never be "Least Time".
  • Tim 1480 Points
    does the Nuvi take into account stop signs and stop lights?
    It is available in the Navteq data. How it is applied or used is undetermined.
  • bill_sc 0 Points
    Nuvi 1200 software 3.70 map 2010.30 set to ‘fastest route’

    Part of my daily commute in Charleston, SC requires driving on hwy 171 from the north bridge 32.830991,-79.988537 to the James Island Connector hwy 30 west 32.776017,-79.962101 Along the way I am told to exit onto Carriage Lane, then turn left after going through an extra stop light to get back onto the same road I was on.
    image
    When I ignore this instruction, I am told to cross two lanes of traffic to the left then pass through local streets before rejoining hwy 171.
    image
    Before map and software update to 3.60, routing was ‘normal’ – stay on the main road.

    Tim, I tried to use your google map, but was unable to save my input. I e-mailed Garmin in February – nothing heard.
  • 10 months, hundreds of posts, multiple map updates, new models, promises to "get back" from tech support and nothings changed.
  • I just turned off the carpool lane avoidance, and it actually helped a little. Before, it was avoiding the interstate like the plague (even with highway avoidance turned off). Now it uses the interstate a little more. It's still not perfect, though.

    They really need an option for people who want to take the interstate as much as possible.
  • dhlizard 0 Points
    I just turned off the carpool lane avoidance, and it actually helped a little. Before, it was avoiding the interstate like the plague (even with highway avoidance turned off). Now it uses the interstate a little more. It's still not perfect, though.

    They really need an option for people who want to take the interstate as much as possible.
    There is: Faster time
  • Marc 301 Points
    This is one of the features I miss from my old Magellan where besides fastest and shortest it had both least and most use of freeways.
  • jimbo68 0 Points
    does the Nuvi take into account stop signs and stop lights?

    It is available in the Navteq data. How it is applied or used is undetermined.
    I have found in extensive travels that the Nuvi does not take into account speed limits, stop signs, etc when computing the fastest route. Recently in a long trip through Fla. my 765t took me off the interstate and through Gainesville, Fl when the interstate ran parallel to this route. The nuvi eventually got me to a connecting route with interstate only 3 miles away. I figure I lost a good 30minutes in traffic. It appears that the shortest route is taken despite the settings. Tim is right. The data is there to use. Garmin's algorithims do not utilize them. I check routes on a map before a long trip and then look at the Nuvi route before I accept it. Sad but that seems to be the state of the art with Garmin.
  • alanb 539 Points
    Jimbo68, do you have traffic avoidance enabled on your 765T? If so is there a chance that your detour off the interstate was because of traffic? It has been a while since I have driven that route, so I don't recall if that area has coverage.
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