Garmin Sat Nav journey time accuracy

Discussion in 'GPS Navigation' started by GJH, Oct 27, 2015.

  1. GJH

    GJH Funster Life Member

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    As posted Here and Here I found that Garmin sat navs tended to underestimate journey times.

    I contacted Garmin support but did not receive a satisfactory reply (unusual for Garmin support in my experience), just advice to make sure the software was up to date (it was) and do a master reset if all else failed. Garmin didn't seem to want to acknowledge that the problem lay in their software.

    As a result I explored on-line support further and found the FAQ "Can I train my Garmin to provide better estimated times of arrival (ETA)?" (http://tinyurl.com/nsqfvth). After reading that I turned on the Travel History feature on both my Nuvi 2569 and Camper 760.

    On October 14/16 we did a return trip to the NEC using our car and the Nuvi 2569 and the ETA turned out to be much more accurate, especially so on the return trip.

    Yesterday we returned from our trip to Blackpool in the van using the Camper 760. We also had a Noza Tec set up for comparison. Both units had the same vehicle profile entered. The ETA calculated by the Noza Tec was pretty accurate but the Camper 760 was, once again, underestimated. I think, though, that I have worked out why. With 59 miles to go on the return journey today, the Noza Tec ETA gave a remaining journey time of 70 minutes (i.e. an average speed of about 60 mph) whilst the Camper 760 ETA gave a remaining journey time of 50 minutes (i.e. an average speed of about 70 mph). The remaining portion of the journey was on the A1/A168/A19.

    This would seem to indicate that the Garmin software uses the maximum speed limit for the roads being travelled, rather than the vehicle being used, to calculate the ETA. That is fair enough for a car alone but is highly likely to be inaccurate when one is driving a motorhome or towing a caravan. Even on a motorway the maximum speed of a car/caravan and heavier motorhomes is 60 mph rather than 70 mph and, as I am sure Garmin is aware, many motorhome drivers restrict their speed to under 60 mph anyway. I would expect, therefore, given that the Camper 760 is supposedly specially designed for use with motorhomes and car/caravan outfits, that it would take that vehicle rather than road limits into account when calculating ETAs.

    I contacted Garmin support again telling them of these findings and asking them to bring this to the attention of their software development team so that they might correct the programming.

    I've had a reply saying they have forwarded my email to the design team "as they are always interested in customer feedback". They won't guarantee that what I have suggested will be implemented but it does seem they aren't just binning it without thought :) We shall see what, if anything, transpires :)
     
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  2. MikeandCarolyn

    MikeandCarolyn Read Only Funster

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    Does it matter ?:LOL:
     
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  3. pappajohn

    pappajohn Funster Life Member

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    My understanding is the device calculates travel time by calculating the maximum speed for any given road within the route then adding the whole route together to give a travel time.
    whether you drive faster or slower will reduce or increase the overall time but it will vary at any given time.
    If you drive at the max speed for all roads you will arrive exactly on time.
    I regularly get to my destination around 10 minutes before my tomtom pulls up along side.
     
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  4. Judge Mental

    Judge Mental Funster Deceased RIP

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    with the traffic in UK being so heavy its not surprising..find it perfectly reliable in Europe, have used garmin since 2000
     
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  5. Judge Mental

    Judge Mental Funster Deceased RIP

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    really on top form today...Bless you:D
     
  6. Gellyneck

    Gellyneck Funster Life Member

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    Would have thought it should be relatively easy for them given BaseCamp has user defined road type average speeds by Activity Profile functionality built in. Why not create this functionality in the sat nav as well?

    I normally use BaseCamp to plan a journey and transfer this to the sat nav. Generally, the sat nav does show a different estimated travel time (quicker) than BaseCamp which would seem to back-up your findings.!
     
  7. Speve

    Speve Funster

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    I suppose it does if you are planning a journey with stop offs as it's difficult to calculate without accurate timing.Out Garmin dezl is hopeless at giving journey times.
     
  8. Speve

    Speve Funster

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    We have not had the same experience ours is still not accurate.
     
  9. MikeandCarolyn

    MikeandCarolyn Read Only Funster

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    :)Images of timed coffee and comfort breaks-how long do you allow?
    What about road traffic problems ? How much do you allow for that ?
    How stressed are you if you get 5 mins behind schedule?
    Happy relaxed Motor Home touring (y)
     
  10. Speve

    Speve Funster

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    We don't get in any hurry,But it's not the tea stops and we are not talking 5 mins and when you are planning to only drive perhaps a couple of hours to An Aire and it gradually stretches to two and a half or three and it's getting dark and you are getting weary an accurate estimate surely is not to much to ask,when I was working I had numerous appointments to keep during the day and to be fair I had a Tom Tom and you could pretty much guarantee the timing was accurate. Garmin don't seem to be as good in that field.
     
  11. GJH

    GJH Funster Life Member

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    In the grand scheme of things it doesn't - unless one needs to make an appointment time or, maybe, not turn up too early for a site arrival time :D
    Exactly. It appears to take only the road maximum into account, not the vehicle maximum which in the case of many motorhomes is lower :D
    That's what I thought as well. It appears that the software specification has not been sufficiently well developed :D
     
  12. MikeandCarolyn

    MikeandCarolyn Read Only Funster

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    Actually I found that last weekend-I just bought Garmin Camper 760 cos my old 1490 died.
    I was driving from Weston to Ludlow by car and Garmin said 2hrs 6mins.
    I got there in 2hrs so damned thing got it wrong !!
     
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  13. TheCaller

    TheCaller Funster

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    My Snooper Ventura is the other way round. I'm assuming it is based on their Truckmate software, with modifications for motorhomes, but despite there being a setting for unladen weight of less than 3.05 tonnes, it seems to give estimates based on HGV speeds. Even when driving in a very relaxed manner, it always overestimates the journey time. In a way, it's quite fun watching the ETA move earlier & earlier as you drive.

    It also has quite a few errors in its speed limit database. It shows a lot of rural roads with a 40 limit when in fact the national limit applies. It may be reasonable to use 40mph in its journey time calculation if it thinks that is correct for the road type & vehicle combination, but it still should show the speed limit as 60 mph.

    I think this is a relatively recent issue, so I'm hoping that a future update will put that part right. It only matters because it beeps at me if I exceed what it thinks the limit is by more than 10mph & 55mph is perfectly reasonable on a lot of the open 'B' roads in Lincolnshire. I could turn the beep off, I expect, but at other times it can be useful!

    EDIT: Just discovered that you can't use the 'less than' character '<' in proximity with the number 3 - it converts it to a heart. As in :h:.
     
  14. davejen

    davejen Funster

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    I've found our garmin to be very accurate, usually to the minute, if we are delayed it resets with a new arrival time, again very accurately, so no complaints from me.
    Cheers, Dave(y)
     
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  15. Judge Mental

    Judge Mental Funster Deceased RIP

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    I find it impossible to recognise this scenario. If its getting dark just find an Aire closer by. I push on, always on or above the speed limit...maybe that's the difference. Have done 20 hour drives to Swedish Lapland and again been spot on. Spain like wise....
     
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  16. MikeandCarolyn

    MikeandCarolyn Read Only Funster

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    Turn your lights on :LOL:
    Sorry,couldn't let that one go by .
     
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  17. Speve

    Speve Funster

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    It's not the hurrying bit but when you are planning a long trip it's really useful to have accurate timings to plan your stops etc, it may sound finicky but that's how we like to do it.
    Everyone to their own.
     
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  18. Judge Mental

    Judge Mental Funster Deceased RIP

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    Thats fine:) The impact of diabetes on ones eye sight means I try to avoid night driving as much as possible
     
  19. Judge Mental

    Judge Mental Funster Deceased RIP

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    still struggling..if I stop for a 20 minute break and then continue, I arrive 20 minutes later... but it will recalculate if you get held up in traffic etc...

    You can double check routes on google maps as well..
     
  20. Speve

    Speve Funster

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    Not worth arguing about!
     
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