This site uses cookies to offer you a better browsing experience. Find out more about how to manage cookies, or dismiss this message and continue to use cookies.

Issues with how Nuvi (765T) calc routes / give directions

Just as a bit of background, I have had a copy of the TomTom Navigator software running on my Palm T|X for years. I really liked how the TomTom worked and navigated... but I wanted to upgrade to a device that had real time traffic. After doing a lot of research, and reading many glowing reviews, I decided on the Nuvi 765T. I loved all of the features such as lane assist and the optional MSN Direct features.

At first, I was very happy with the Nuvi. The first time I used it was in Las Vegas... where the real-time traffic came in very handy. I also loved the lane assist and being able to look up movie times with MSN Direct. But, then I started using it around home... mostly just for fun to see if it could find any fancy new directions to my favorite spots. What I found is that the Nuvi greatly underestimates the amount of time it takes to travel over city streets. For example, it takes about 30 minutes for me to travel to my girlfriends house. Yahoo, Google, Bing and my Navigator all pretty much agree on the best way to get there... which is nearly all freeway driving.

The Nuvi on the other hand, has me exiting the freeway about half way there and taking city streets. I thought this was strange, but tried it anyway. Sure enough... it took about 10 minutes longer to get there than it does going my normal route. I've also tested with other locations and found the same thing... Nuvi just doesn't seem to take into account that city streets have traffic and stop lights. But somehow, my ancient TomTom and Yahoo/Google/Bing know what the deal is.

My other issue is on how my Nuvi gives directions when you enter an interchange of highways. Let's say you are on Hwy A going east and you need to go south on Hwy B. At the interchange, there is a separate exit for Hwy B North (let's call it exit 123A) and one for Hwy B South (exit 123B). Since the north exit is a few yards ahead of the south exit, Nuvi will say "In 1 miles, keep left on Hyw A". After you pass the exit for Hwy B north, it will say "In 70 feet, take exit 123B...". Well... at freeway speeds you have no way of making that exit. Again my old Navigator has no problem recongizning this and just tells you to take exit 123B right away. I've noticed this at many interchanges.... especially where there is an freeway exit on the left and on the right.

These issues make the Nuvi almost worthless for me. I cannot trust it to give me the fastest route... and I cannot rely on it telling me the directions I need in time to execute them. I guess mostly I'm just venting here... but I'm wondering if anyone else has experienced the same things I have. I also wonder if there are any "insiders" that might know if Garmin might have some fixes in the works. I wouldn't think it would be too difficult to correct. Let me know your thoughts and sorry about the lengthy post!!

Comments

  • Yep, you are venting !!! :lol:


    just talked to a guy that his did the same thing - took him off the interstate and then around a turn then a u turn.....he said he'd never buy another .... Tom-Tom :shock: :lol: :lol:

    So it's the old "What is the best " ?

    For some reason, when it tells me to turn in 1 mile which takes 1 minute to traverse @ highway speeds, I give a signal and start slowing down :)

    but my 765T tells me in .5 miles, in .1 mile,
    then it starts showing the turn distance in feet to turn...

    So it's not a problem for me -
    or my two Bro-in-laws that have the same maps, and gps...

    to your point about worthless - send it to me so it doesn't bother you anymore !!!

    re the fastest route,
    is it possible you have some avoidances set ? like traffic ?

    re time to arrival? why not leave 10 minutes earlier :)

    But mostly if I KNOW where something is, I could care less about which way the gps sends me, cuz I'm not using it for that...

    Now for those places I don't know where they are... I really won't know if it's the "right" way... good luck !
  • garddog32 0 Points
    Yep, you are venting !!! :lol:


    just talked to a guy that his did the same thing - took him off the interstate and then around a turn then a u turn.....he said he'd never buy another .... Tom-Tom :shock: :lol: :lol:

    So it's the old "What is the best " ?

    For some reason, when it tells me to turn in 1 mile which takes 1 minute to traverse @ highway speeds, I give a signal and start slowing down :)

    but my 765T tells me in .5 miles, in .1 mile,
    then it starts showing the turn distance in feet to turn...

    So it's not a problem for me -
    or my two Bro-in-laws that have the same maps, and gps...

    to your point about worthless - send it to me so it doesn't bother you anymore !!!

    re the fastest route,
    is it possible you have some avoidances set ? like traffic ?

    re time to arrival? why not leave 10 minutes earlier :)

    But mostly if I KNOW where something is, I could care less about which way the gps sends me, cuz I'm not using it for that...

    Now for those places I don't know where they are... I really won't know if it's the "right" way... good luck !
    As far as the issue with the highway exits, the issue happens when you have multiple exits right on top of one another... especially when you have one on one side of the highway and the next on the other side. Normal highway driving is not an issue.

    I'm glad your not concerned with how long of a route your GPS plans for you... but for the $$$$ we're spending on these higher end units... I guess I expect a little more.... especially since everyone else seems to be able to it better.
  • brighttng 0 Points
    I will have to agree on this. Garmin seems to really underestimate the actual time it will take to travel on local roads. I have found in many circumstances that other GPS like Tomtom would choose to travel on high ways, interstates while Garmin thinks the best route is to take local roads, at least for part of the calculated route. But usually the actual time it takes to travel on these local roads is longer than what Garmin has predicted due to traffic lights and traffic.

    I think Garmin really needs to improve its algorithm or heuristics of its routing.

    PS: my GPS is a Garmin 265T.
    Just as a bit of background, I have had a copy of the TomTom Navigator software running on my Palm T|X for years. I really liked how the TomTom worked and navigated... but I wanted to upgrade to a device that had real time traffic. After doing a lot of research, and reading many glowing reviews, I decided on the Nuvi 765T. I loved all of the features such as lane assist and the optional MSN Direct features.

    At first, I was very happy with the Nuvi. The first time I used it was in Las Vegas... where the real-time traffic came in very handy. I also loved the lane assist and being able to look up movie times with MSN Direct. But, then I started using it around home... mostly just for fun to see if it could find any fancy new directions to my favorite spots. What I found is that the Nuvi greatly underestimates the amount of time it takes to travel over city streets. For example, it takes about 30 minutes for me to travel to my girlfriends house. Yahoo, Google, Bing and my Navigator all pretty much agree on the best way to get there... which is nearly all freeway driving.

    The Nuvi on the other hand, has me exiting the freeway about half way there and taking city streets. I thought this was strange, but tried it anyway. Sure enough... it took about 10 minutes longer to get there than it does going my normal route. I've also tested with other locations and found the same thing... Nuvi just doesn't seem to take into account that city streets have traffic and stop lights. But somehow, my ancient TomTom and Yahoo/Google/Bing know what the deal is.

    My other issue is on how my Nuvi gives directions when you enter an interchange of highways. Let's say you are on Hwy A going east and you need to go south on Hwy B. At the interchange, there is a separate exit for Hwy B North (let's call it exit 123A) and one for Hwy B South (exit 123B). Since the north exit is a few yards ahead of the south exit, Nuvi will say "In 1 miles, keep left on Hyw A". After you pass the exit for Hwy B north, it will say "In 70 feet, take exit 123B...". Well... at freeway speeds you have no way of making that exit. Again my old Navigator has no problem recongizning this and just tells you to take exit 123B right away. I've noticed this at many interchanges.... especially where there is an freeway exit on the left and on the right.

    These issues make the Nuvi almost worthless for me. I cannot trust it to give me the fastest route... and I cannot rely on it telling me the directions I need in time to execute them. I guess mostly I'm just venting here... but I'm wondering if anyone else has experienced the same things I have. I also wonder if there are any "insiders" that might know if Garmin might have some fixes in the works. I wouldn't think it would be too difficult to correct. Let me know your thoughts and sorry about the lengthy post!!
  • garddog....
    Apologies if you mistook the tone of my post...

    It's all good !
    As many have said, "the best way" is different for different people :)

    Give Garmin a call or post on their website to see what they say ....

    maybe there is a fix ....
  • bengele 0 Points
    I don't recall this specifically happening on my 765 (though I expect that it does) but on my older Garmins if there was an interchange like the one you described it would say something like "keep left then exit right" before the first part of the interchange. Are you sure it did not do something like that?
  • garddog32 0 Points
    I had one happen to me yesterday, where it said "keep left on (hwy name). Exit ahead". It did not specify a left or right exit... and there was one on both sides. I think it does what you say when you are actually exiting the highway and then you have another quick exit right after that.
  • JIM C 0 Points
    I have a Nuvi 760 and I have a puzzling case of this keep left guidence.

    I travel the PA turnpike quite often. I usually drive from the West Chester/Downingtown exit to the Harrisburg West exit about 65 miles one way.

    When going West bound, everything is fine, my next turn is in 65 miles. When going East bound (from Harrisburg to West Chester), I get a message to keep left on I-76 East (PA Turnpike), at the Morgantown interchange (about 15 miles from the West Chester exit).

    My first thought was perhaps it had to do with the confusion of route I-176 at the exit but then why wouldn't it say this coming in the opposite direction of travel? My other thought is that there was construction at one point and maybe the map was never updated yet.
  • garddog32 0 Points
    I had another troubling instance of bad route calculation. I was at a campgrounds where I pretty much new the best way home. I asked the Nuvi to calculate a route, and it had me go down a road I would not have ever guessed to go. It also said the trip would take 30 minutes, where the way I normally go takes about 10. So, I ignore the Nuvi and turn down the road I normally would have.. and sure enough it recalculates and says my trip time is now 10 minutes. I don't have any avoidances set... so why would it make such a large mistake. I think it is time to open a support call with Garmin to see what is up.
  • I will have to agree on this. Garmin seems to really underestimate the actual time it will take to travel on local roads. I have found in many circumstances that other GPS like Tomtom would choose to travel on high ways, interstates while Garmin thinks the best route is to take local roads, at least for part of the calculated route. But usually the actual time it takes to travel on these local roads is longer than what Garmin has predicted due to traffic lights and traffic.

    I think Garmin really needs to improve its algorithm or heuristics of its routing.

    PS: my GPS is a Garmin 265T.
    Have to disagree im afraid. My 765t is almost always accurate to within a couple of minutes (thats over 70 mile trips!), even when theres traffic eg rush hour. Tomtoms on the other hand, I find the accuracy laughable
  • wilsonhp 0 Points
    I have similar issues with my 755t. I commute daily across Minneapolis/StPaul. I know the best route is straight across the middle. Yet invariably, my Nuvi wants me to go around the loop to the north. Each time I ignore the instructions and go my way, the estimated time to my destination decreases. It also wants to take me off of clear interstate highways, and onto local highways which are clearly showing traffic delays on the traffic alerts. I can take 5-8 minute off of a 45 minute commute by not going the way Nuvi wants to send me.

    I don't get it. But I run it daily for the traffic features.
  • grease 0 Points
    Devil is in the map details. Some areas have better mapping data then others. Garmin doesn't make maps, NAVTEQ does. In the US NAVTEQ maps generally considered better then competition even though there are plenty of problems that are not being resolved even with quarterly map updates.
  • Hexagonal 0 Points
    Hi -- I've got the same model as the OP. [Well, I've got the 775T, not the 765T - my understanding is that the only diff. is the pre-loaded Europe]

    I see your points, and I mainly agree with you. The main big city I drive through is Atlanta, GA.

    Three comments:

    (1) I see the difference in predicted arrival time and actual arrival time consistently. When more than about 5 lights are involved, I get where I'm going between 20% and 30% later than the Garmin thinks I should. My take on this is that it's not a problem with Garmin, it's a measure -- a very accurate measure -- of just how bad the traffic light synchronization is in greater Atlanta.

    In other words, since getting my nuvi I can not only bitch & moan about the so-called "traffic engineers" who set up the light timings here -- I can prove, with numbers, just how much time I'm losing due to their incompetence. Lately I've been letting a little clipboard ride shotgun with me, and I note just where the lights with the worst "dead time" are -- those lights where, consistently, NO ONE is going for long stretches at a time b/c you're stuck at a red and there's no cross traffic. I'm saving the info up for a detailed write-up which I'll send to the local governments, the newspaper, and my State Reps.

    We can all do this. We can lobby our local governments for more intelligent light design -- variable timing, more buried sensors, etc. -- using the info we get from our Garmin to back up what we know already with some hard data. I'm not expecting miracles here, but I know from experience that you can succeed in nudging local governments to do their job when you have a strong case backed up with real info.

    (2) NAVTEQ has improved the way you can report to them errors in the base map. I haven't been doing this long enough to have any confidence that they actually DO anything with the info you report, but it's worth a shot. Their "Map Reporter" website is:
    http://mapreporter.navteq.com/dur-web-external/secured/submitDur.do?userType=CONSUMER&language=en
    If you've got map inaccuracies on routes you drive a lot, report them.

    (3) I remember seeing it asserted somewhere that the 700 series actually learned your particular driving style over time. Is this BS or have any of you actually seen any evidence of this? If it does learn, then the gap between predicted arrival time and actual arrival time should shrink the more often you set a particular location. I've been setting locations I already know how to get to for weeks now, in the hope that the unit would "learn" more accurately how long it takes to get there. Haven't noticed anything yet.

    Actually, if the "learning" thing is real that's one more reason the owners with recently bricked 7xx's should be pissed off. All that precious learning, lost!
  • gatorguy 326 Points
    #3. Yes it's a fact, confirmed by Garmin themselves after our testing had already proven it.
  • It's hardly all that advanced of an algorithm from my understanding. What they ought to do if they aren't going to work on implementing a historical road speed-based routing system (a la TomTom's fantastic IQ Routes) is start learning now based on the recorded speed limits for roads where available. It would be easy to write:

    Record driver's average speeds on 25 mph roads...
    Record driver's average speeds on 35 mph roads...
    Record driver's average speeds on 45 mph roads...

    And so on. If the speed limit data is unavailable, the nuvi could revert to the old method of values based on street type (collector streets, highways, etc.). THAT's all there is to the current "learning" method, so it's hardly some sort of breakthrough. Heck, you can set the values yourself in Mapsource.

    Even worse however is the fact that the nuvis don't seem to estimate stoplights and turns properly at all. Left turns are horribly underestimated in time penalty and, honestly, nearly every major intersection on a road ought to be figured as having a stoplight. Again, it would be easy to implement. Simply estimate a specific amount of time per stoplight at every intersection of every major road. This would be an average, of course, so it would take into account those instances where the stoplight is actually green or when no stoplight is present at all (the latter probably not being so often, as most major intersections have a stoplight).

    As a programmer myself, as well as a previous user of both a TomTom and a Magellan GPS, I think the nuvi's routing algorithm could use a lot of work. It's about on par with the Magellan, but the TomTom's got it beat hands-down with its IQ Routes. I sure hope Garmin's got something up their sleeve here, or at least they decide to allow a bit more customization of the routing algorithm variables by users in the future (not likely).

    Steve
  • gatorguy 326 Points
    For all it's flaws it seems pretty accurate over most of my travels. Even on 100 mile + journeys it's generally within 3 minutes or so of the originally computed travel time. And because of Garmin's learning algorithm, my two year old nuvi 760 is more accurate than my TomTom's in computing travel times over two specific classes of road: Primarily Interstate drives, and rural/country roads. Best of both worlds would be to combine Garmin's use of my real travel speeds with historical flow data.
  • BullieverBulliever 0 Points
    I think the nuvi's routing algorithm could use a lot of work. It's about on par with the Magellan, but the TomTom's got it beat hands-down with its IQ Routes.
    Steve
    You have me puzzled....If TomTom is "all that and a bag of chips", then why in the world did you buy a crummy Garmin?
  • No need to be puzzled. Every major source seems to prefer the Garmin. In fact, other than the aforementioned routing issues and some missing options, I even prefer the 755T I now own. It's possible to be unimpressed with one aspect of a product and still appreciate others. I should know; I review videogames professionally. :)

    Steve
  • BullieverBulliever 0 Points
    No need to be puzzled. Every major source seems to prefer the Garmin. In fact, other than the aforementioned routing issues and some missing options, I even prefer the 755T I now own. It's possible to be unimpressed with one aspect of a product and still appreciate others. I should know; I review videogames professionally. :)

    Steve
    All well and good, however determining routes is the primary function of a PND...seems silly to go with one that you have determined to be not on par with a another vendor's product. "TomTom's got it beat hands-down with its IQ Routes."

    I've had a 755T since early December of last year and a I'm not impressed in the with it's routing choices. After extensive travel using it, it now spends most of its time in the off mode and used only in what I would call "spur of the moment - I'm not sure how to get there from here" use only.
  • All well and good, however determining routes is the primary function of a PND...seems silly to go with one that you have determined to be not on par with a another vendor's product.
    Yes; if only I had known that prior to my purchase.

    But I really only partially regret it; in many ways, this Nuvi is in fact better than the TomTom. It's really just a matter of give and take I think... though I do miss the intelligent routing.

    Steve
  • garddog32 0 Points
    For all it's flaws it seems pretty accurate over most of my travels. Even on 100 mile + journeys it's generally within 3 minutes or so of the originally computed travel time. And because of Garmin's learning algorithm, my two year old nuvi 760 is more accurate than my TomTom's in computing travel times over two specific classes of road: Primarily Interstate drives, and rural/country roads. Best of both worlds would be to combine Garmin's use of my real travel speeds with historical flow data.
    I would think the issue with Garmin's navigation "flaws" would be less noticable the longer your trip is. The longer your trip, the more likely you are going to be on long stretches of highway that even the Garmin cannot dispute are faster than city streets. The problem for me at least is the navigation routes that are calculated once you get close to your final destination and need to (at some point) hit local road.

    I do agree with one point... the Garmin does do a much better job than the TOMTOM on caclulating travel time. My old TOMTOM would always over estimate how long it took to get somewhere by quite a bit. However, my TOMTOM would get me there faster.
  • I recently got a 765T to replace a Magellan 4060. The Magellan would generate flaky routes (not just suboptimal, but broken: e.g. a perfect route, except where I should turn left I'm routed straight, taken on a 45 min. loop back to the intersection I should have turned left at, and then directed back onto the correct route).

    The Magellan always overstated the travel time by around 10 to 15 minutes, while the Garmin is very accurate. The Garmin generally gives slightly better routes than the Magellan (when it's not misbehaving).

    I'm generally very happy with the Garmin. The only Magallan feature I miss is the diagram that shows several quick turns in succession. E.g. If there's a freeway exit, then a quick bear right, then a left, the Magellan will show that in a single diagram. The Garmin doesn't have that feature. The Garmin does have much better menus, lane assist, and free traffic info, and doesn't have the annoying "Continue on current route" prompt.

    Mike
Sign In or Register to comment.
↑ Top