Why is route planning so poor?

Kremmen · Posted: Thu Oct 05, 2017 10:02 am Post subject:

Totally agree.
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pcaouolte · Posted: Thu Oct 05, 2017 10:21 am Post subject:

When selecting fastest route on a Garmin it does not always offer the fastest route that is available. Sometimes you can add a via point after asking for the fastest route and it will reduce the time to travel. This should not be possible if the Garmin has already offered the fastest route available.

It appears to me that the Garmin has some algorithm which prevents it offering the fastest route if it would add significantly to the distance traveled. This is logical in some circumstances but the Garmin seems to take it to extremes. Sometimes routing off a main road onto a back road and back onto the same main road to save 0.1 miles and add 1 minute to the fastest available main road route.

An internet search reveals that people have been complaining about Garmin's routing since at least 2010 with the same issues that people are complaining about in this thread. It doesn't seem that they intend to fix it.
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Paul

sussamb · Posted: Thu Oct 05, 2017 10:24 am Post subject:

Privateer · Posted: Thu Oct 05, 2017 10:35 am Post subject:

I admit to being a Garmin newbie. Laughing

However, my wife and I have only recently returned from a fortnight's holiday in Jersey, Channel Islands. I had both the TomTom and Garmin running. The TomTom chose the more logical (i.e. quickest, most direct, least number of roads).

Jersey is a good place to test a SatNav as it has loads of roads so you can take many different roads to get to the same place. A lot of the roads are narrow with hairpin bends.

I have the Garmin Camper 770 LMT-D so I'm able to change the vehicle's dimensions and weight so a little tweaking helped but it's difficult to get an optimum setting.

The TomTom has good routing, traffic, and uses road names, the Garmin is better in other respects. If we could have a hybrid of the best TomTom/Garmin features then we would have a killer SatNav! Thumbs Up

sussamb · Posted: Thu Oct 05, 2017 10:45 am Post subject:

There are similar TT threads about the older models. Nothing is ever perfect for everyone Wink

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M8TJT · Posted: Thu Oct 05, 2017 11:20 am Post subject:

But the point is, it could be a lot better.
On a certain route, my Garmin routes me down a lane that even streetview vans haven't ventured down. Shocked

topref · Posted: Thu Oct 05, 2017 12:47 pm Post subject:

Not exactly being routed on to an unclassified road then rejoining a main carriageway but shows the ridiculous Garmin route planning. The main road is a 20mph quarter of a mile stretch past a school but there is a 50 - 100 yard stretch running alongside subject of a 30mph. It would take time to turn right on to the 30mph road then having to wait for a break in the traffic to rejoin the main road again. This picture says it all (I hope it can be seen):

https://imgur.com/a/TUvQl

sussamb · Posted: Thu Oct 05, 2017 1:12 pm Post subject:

While you can see it's nuts a machine simply sees nodes joined by lines. Personally I'd have been looking at the map and just gone straight on, as I suspect most of us would do.
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Kremmen · Posted: Thu Oct 05, 2017 1:28 pm Post subject:

sussamb · Posted: Thu Oct 05, 2017 1:34 pm Post subject:

Yes, may get a response. Even better if you could suggest how it could be avoided?
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topref · Posted: Thu Oct 05, 2017 1:35 pm Post subject:

sussamb · Posted: Thu Oct 05, 2017 2:06 pm Post subject:

Agreed, that's more of an issue.
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Dabri · Lifetime Member Joined: Aug 30, 2006 Posts: 149

With reference to topref's routing image.

On my first test (from SA14 6DT to 82, Behania Road) my 3598 and 2460 both followed the Kew Garden route, although clearly a driver option to ignore. On a second test (from the same starting point, but this time to 56, Bethania Road) the 3598 kept to the main road - I wonder why.

My 2460 at least does allow me to adjust Kew Garden's default speed down to 5 mph; at which point the 2460 route ignores Kew Gardens - (sarcastic) hooray.
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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 · Posted: Thu Oct 05, 2017 3:19 pm Post subject:

That is a mapping problem.

"Here" have the average speed on that section of Bethania Road as less than 20 mph whilst the average speed for Kew Gardens is less than 30 mph. The Garmin is just calculating that Kew Gardens at 30 mph will be faster than Bethania Road at 20 mph and giving the fastest route that it can find with the data that it has available.

Edit: Actually looking at TopRefs comments above the map is probably correct and therefore the fastest route that can be calculated is probably the one offered by the Garmin. It will depend on how much time the Garmin adds for the right turns required to take the 30mph road.
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Paul

M8TJT · Posted: Thu Oct 05, 2017 3:46 pm Post subject:

How do you find the speeds for various road as you have done?

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