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walkerx Lifetime Member

Joined: Oct 21, 2009 Posts: 494 Location: South Yorkshire
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Posted: Mon Apr 17, 2017 7:39 pm Post subject: Garmin Routing |
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So far these past couple of days, the Garmin has proved how bad it is at routing.
On A1 heading towards Kielder it told me to take a right turn onto a non existent junction. I later found that the junction we actually wanted was quite a distance prior to the one it notified me of yet never actually mentioned to take.
Next it was taking me of main a roads to go along b roads and county lanes, to only take me back onto the a road it had taken me off, which would have only taken 5 minutes instead of the 20 minutes.
Then today it took me down a road that became a private road to a dead end to a field.
And they wanting to use satnavs for driving tests... Big mistake........ |
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sussamb Pocket GPS Verifier

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Joined: Mar 18, 2011 Posts: 4462 Location: West Sussex
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Posted: Mon Apr 17, 2017 8:43 pm Post subject: |
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You should try asking my wife to navigate  _________________ Where there's a will ... there's a way. |
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cjay2412 Lifetime Member
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Joined: Jun 30, 2008 Posts: 103
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Posted: Mon Apr 17, 2017 10:42 pm Post subject: |
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having used both tomtom and Garmin for navigation whilst neither are perfect on all occasions tomtom is superior for a-b routeing although Garmin is slowly closing the gap with each map update there is still some catching up to do |
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walkerx Lifetime Member

Joined: Oct 21, 2009 Posts: 494 Location: South Yorkshire
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Posted: Mon Apr 17, 2017 10:55 pm Post subject: |
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sussamb wrote: | You should try asking my wife to navigate  |
Lol, same as my wife
I hope they also update their maps and junction views and lane guidance to take into account the new smart motorways |
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Kremmen Pocket GPS Verifier


Joined: Mar 03, 2006 Posts: 7191 Location: Reading
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Posted: Tue Apr 18, 2017 5:41 am Post subject: |
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I wonder why Garmin make these silly mistakes. They've been around long enough to have this sorted by now. _________________ DashCam:
Viofo A119 V3 |
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Allan_whoops Frequent Visitor

Joined: Feb 18, 2006 Posts: 369
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Posted: Tue Apr 18, 2017 7:09 am Post subject: |
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I've used both TomTom and Garmin recently as well as various smartphone apps. They all have the same problem. I think it is down to the maps now having speed limits attached to roads so the system 'sees' a 60 mph limit for a single track road as well as a major A road. Therefore the single track road appears quicker if it is shorter.
Even Mapfactor Navigator, which allows adjustment of speed for each type of road, doesn't handle this very well. |
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pcaouolte Frequent Visitor

Joined: Dec 27, 2006 Posts: 998 Location: South Lincs, UK.
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Posted: Tue Apr 18, 2017 8:05 am Post subject: |
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Recently in the Lake District my Garmin tried to take me down exactly the same unsuitable road that a TomTom had tried to take me down previously.
I would never take a car down this road, it would be ok for a tractor, it is very narrow and full of large pot holes.
On the maps it is marked as a road and it doesn't have a speed limit so sat navs probably assume that you can do 60mph along it.
I think that I have seen a facility on the Garmin to set an area to avoid, I wonder if I can use this to make the Garmin avoid that road in future but I haven't tried this yet. _________________ Paul |
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Allan_whoops Frequent Visitor

Joined: Feb 18, 2006 Posts: 369
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Posted: Tue Apr 18, 2017 8:15 am Post subject: |
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Yes, you can block off roads and whole areas. However, you will have to repeat the exercise if you do a master reset. |
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MaFt Pocket GPS Staff


Joined: Aug 31, 2005 Posts: 15356 Location: Bradford, West Yorkshire
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Posted: Tue Apr 18, 2017 8:27 am Post subject: Re: Garmin Routing |
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walkerx wrote: | On A1 heading towards Kielder it told me to take a right turn onto a non existent junction. I later found that the junction we actually wanted was quite a distance prior to the one it notified me of yet never actually mentioned to take. |
I think I know where you mean - and I took that exact route around August last year! At the time, the actual road was still being worked on. I don't think the issue is with the routing itself, but with out of date map data.
A SatNav can only be as accurate as the data it has.
Last edited by MaFt on Tue Apr 18, 2017 8:43 am; edited 1 time in total |
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M8TJT The Other Tired Old Man


Joined: Apr 04, 2006 Posts: 10118 Location: Bexhill, South Sussex, UK
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Posted: Tue Apr 18, 2017 8:33 am Post subject: |
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The algorithm is simple. Don't route down B roads if there is an A road available even if it is a bit longer. Same for B/C road routeing.
Don't assume that NSL is achievable on a B road as invariably it isn't so revisit the satnav's assumption of speeds on B/C roads.
As Kremmen said, both Garmin and TomTom have years of experience and must have had thousands of complaints about this, so WTF haven't they got it sorted?
I'm sure it ain't easy, but I'm also sure it ain't rocket science either. |
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Daggers Lifetime Member

Joined: Jun 20, 2005 Posts: 1096 Location: Solihull, UK
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Posted: Tue Apr 18, 2017 9:03 am Post subject: |
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I think the routing algorithm is much more complex than looking at the speed limits of the roads. I seem to recall reading somewhere that each road is divided into segments which have an average driving time associated with them. It's then a case of looking at all the options and calculating the cumulative driving time.
The problem comes where some of these driving times are inaccurate. On a dual carriageway, the driving time should equate to something near 60mph, while on an A road, it will be less, and on a B road, significantly lower, although each road will have its own timings. _________________ Garmin DriveSmart 50 LMT-D |
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marksfish Pocket GPS Verifier


Joined: Jun 25, 2005 Posts: 802 Location: Sandy, Bedfordshire
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Posted: Tue Apr 18, 2017 9:48 am Post subject: |
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Allan_whoops wrote: | Yes, you can block off roads and whole areas. However, you will have to repeat the exercise if you do a master reset. |
And after map updates. Makes it very difficult to add the road to an area you don't travel to very often and my forget about  _________________ Garmin Drivesmart 51 LMT-D Europe |
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Kremmen Pocket GPS Verifier


Joined: Mar 03, 2006 Posts: 7191 Location: Reading
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Posted: Tue Apr 18, 2017 9:54 am Post subject: |
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One of the pitfalls is asking for the shortest route. It does just that in a silly way.
I've still got the last, now obsolete, Microsoft MapPoint and that does a superb job. It never uses daft side roads when faster roads are available even if longer. Shame the data can't be transferred. _________________ DashCam:
Viofo A119 V3 |
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cottonsocks Regular Visitor

Joined: Apr 29, 2010 Posts: 189
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Posted: Wed Apr 19, 2017 3:58 pm Post subject: |
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marksfish wrote: | Allan_whoops wrote: | Yes, you can block off roads and whole areas. However, you will have to repeat the exercise if you do a master reset. |
And after map updates. Makes it very difficult to add the road to an area you don't travel to very often and my forget about  | This process would be a whole lot simpler if it could be done on a PC, such as through BaseCamp. Then, it would be a simple matter of reloading the data if it got cleared by an update. Trying to add roads to avoid via the sat nav screen is tedious as you can't even use a search facility to put the map in roughly the right loaction. |
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cottonsocks Regular Visitor

Joined: Apr 29, 2010 Posts: 189
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Posted: Wed Apr 19, 2017 4:04 pm Post subject: |
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Kremmen wrote: | One of the pitfalls is asking for the shortest route. It does just that in a silly way.
I've still got the last, now obsolete, Microsoft MapPoint and that does a superb job. It never uses daft side roads when faster roads are available even if longer. Shame the data can't be transferred. | I hate with a passion, those narrow, pot-holed country lanes, which are totally unsuitable for cars. Even during the daytime it's a right pain if meeting something coming the other way, but on a wet night it would be complete nightmare. I find it hard to believe that the leading sat nav manufacturers like Garmin & TomTom haven't got their routing algorithms spot on by now. We pay enough for their products and yet we are being let down badly by poor routing. When are they going to get this sorted? |
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