Why is route planning so poor?

[Kremmen]

If you're doing a long unknown journey it sounds like the procedure needs to be:

1) Plot the journey indoors
2) Check it, put in avoids if necessary
3) Recalculate

Then, if you get and accept a traffic diversion enroute = recalculate, it should still recognise your avoids.

The bottom line here, to me, is that Garmin insist on putting the NSL of 60mph on all unclassified country roads.
Technically correct but if you meet a tractor coming the other way ........

Like this live example from near Seaford on the south coast:



Right here: google maps link
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Satnav:
Garmin 2599 LMT-D (Indoor test rig)
DashCam:
Viofo A119 V3
Car Average MPG :

[sussamb]

To be fair it's not Garmin but those who specify speed limits on our roads. If unclassified roads weren't NSL but 30 or 40 mph ...
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Where there's a will ... there's a way.

[M8TJT]

But if Garmin use the nationally allocated speeds in their algorithm, that's stupid and I doubt that they do. They need to re-visit the speeds that they assign to different road types and perhaps make it user settable even if it's hidden away in the Vol ~ Long press menus somewhere.
Other satnavs (Honda, iGO) allow you to change road speeds by road type and it makes a difference to the routeing (on iGO anyway). Set a speed of 10MPH on C roads and it will not route on them, (if other faster alternatives are available) set speed to 60MPH and it will.
It's a Garmin's (an others) problem, not those who set the nationally allocated road speeds.
You are trying to defend the indefensible again suss.

[sussamb]

That would be one way but you and others need to make the suggestions to Garmin rather than here. As I said above, you can change speeds for numerous road types in BaseCamp, would be good if the same could be done on the device.
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Where there's a will ... there's a way.

[M8TJT]

[sussamb]

Not defending or not anything. Routeing has rarely been an issue for me, and often its users expecting far too much or not understanding their device. However if it helps some folks a setting that allows speeds to be set for certain road types is one way a user could influence routes, or perhaps some avoidance additions, eg avoid unclassified roads.

However I don't see enough demand for a change so would be surprised if Garmin made any changes, in the meantime I'll stick to my way of planning routes as it works for me
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Where there's a will ... there's a way.

[Oldboy]

[M8TJT]

Don't have a problem with that idea, but how is the 'Time to travel' arrived at?
If it's T=D/S and if the 'national speed limit (for the type of road)' is used as S, you are on a hiding to nothing.

[Oldboy]

My understanding is that the road is classified, as Motorway, Urban Motorway, etc. down to Minor Road and 'Other'.

This can be used, instead of speed alone, to achieve a travel time. Also a Right Turn has a greater time factor than a Left Turn.
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Richard

TT 910 V7.903: Europe Map v1045
TT Via 135 App 12.075: Europe Map v1120

[Allan_whoops]

This is one the reasons why I moved to a phone app. Something like Mapfactor allows you to define the speeds on each type of road and whether you wish to use them.

[Dabri]

From what I can tell (and I may well be wrong) there are 11 (eleven) classifications of roads on my nuvi.
These are: [1] INTERSTATE; [2] SS INTERSTATE; [3] HIGHWAY MAJOR; [4] HIGHWAY MINOR; [5] ROAD ARTERIAL; [6] ROAD COLLECTOR; [7] ROAD RESIDENTIAL; [8] ROAD RAMP; [9] ROAD TRAIL; [10] ROAD ALLEY; [11] ROAD UNPAVED.
I have also noted that some of these (e.g. alley. trail, unpaved) are not consistent with (my) reality, so that even if all three were somehow excluded from routes some single tracks may by used if they were mislabelled, say residential by the map makers (and they are).
Even setting speed limits by road type may also fail due to mislabelling. The only solution that partly worked for me was the ability to set individual road speeds, as found on the 2460 - but, generally only applicable after a problem has arisen.
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Dabri.
Navman iCN530T; Garmin 760T v4.80; Garmin 765T v4.00; Garmin 2460LMT v3.60; Samsung S3;
Garmin 3598LMT-D v5.50; Samsung J6; Garmin DriveSmart76 LT-D v6.80; Samsung A52.

[pcaouolte]

It may vary by country. In the UK "Here" (Garmin's map provider) allows you to select one of 8 road types; Highway, Main, Local Access, Residential, Parking Lot Road, Pedestrian Zone, Pedestrian Road or Trail. Each road segment can have an average speed allocated to it. Outlook Avenue in Kremmen's post above has an average speed of less than 20mph allocated to it which looks reasonable.
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Paul

[M8TJT]

So it seems that it is Garmin that is not fully using the data that it has available?

[Kremmen]

It would seem that way, given the posts where someone has been taken off an A road onto a single track, then back onto the same A road further along.

I'm still suspicious of a 'shortest route' preference.

Whilst SatNavs can produce a shortest route it needs to be sensible. Not these silly scenarios where it takes you off a motorway, down and up a junctions slip roads because it's 20 yards shorter.
_________________
Satnav:
Garmin 2599 LMT-D (Indoor test rig)
DashCam:
Viofo A119 V3
Car Average MPG :

[Privateer]

As far as intelligent routing is concerned, I believe that TomTom is currently better than Garmin. This may be due to how each of them uses historical anonymous data.

TomTom has IQ Routes
Garmin has traffic trends (I think)

It's already been pointed out that in the UK, if a road doesn't have a marked speed limit then it'll probably have an NSL roundel. Unfortunately SatNavs tend to associate NSL with 60mph and therefore also free flow of traffic which most certainly isn't the case on a twisty single land road in the middle of nowhere.

Both Garmin and TomTom produce products for trucker drivers which should avoid narrow roads (unless making a delivery there). So Both Garmin and TomTom should give their car SatNavs a little more information about single track roads in the map data and also an option to avoid single tract roads unless the destinations on the single track road.

Regards,
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Robert.
iPhone 6s Plus, iOS 14.0.1: iOS CamerAlert v2.0.7
TomTom GO Mobile iOS 2.3.1; TomTom (UK & ROI and Europe) iOS apps v1.29
Garmin Camper 770 LMT-D

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