Driving in the English countryside with the Garmin Quest.

[Shaolyen]

I've had my Quest for a few months now, and for the most part I've enjoyed using it. But living out in the middle of nowhere has made me realise that there's a big flaw in the way the Quest works, and it's driving me up the wall (no pun intended).

Here's the problem. Out where I live there are plenty of big roads, but there are numerous tiny roads which connect villages and provide alternative routes to bigger towns. The problem is that these roads are just about the width of my rather small car, the sort which means you have to drive up onto the side if another car comes the other way. The Quest vastly overestimates the average speed possible on these roads, which can sometimes be as low as 10mph on the bendy bits... sometimes sending me off into the middle of nowhere when I know there's a much faster route elsewhere. (On a road which can support more than one car width.)

In MapSource, I've noticed that there are fields to enter your average speeds on certain types of road. Something like this would be great, but it just doesn't carry over to the Quest.

Does anyone know of a way to somehow lower the speed my Quest thinks I can drive on these roads, so it chooses the a faster route when possible? Please help, I'm desperate!

[Skippy]

[Shaolyen]

[Skippy]

Can you post some examples of the routes so we can try it?

If you want to find out the road speeds, try this:

Go to the GPS Info screen, press menu, Use Indoors.

Then press Menu, New location and select the start point for your trip as the new location.

Now use the Find option to route to your destination.

After the Quest has calculated the route, it should ask if you want to simulate driving this route. Select Yes.

Now switch to the trip computer screen and you can see your speed. (Or change one of the fields on the map screen to show speed). This should give you an idea of the speed it is using for each road.

Hacking the firmware wouldn't be for the faint hearted but I would be interested to know if you actually find out where the speeds are stored.

I was under the impression that the Quest uses some adaptive algorithm for the speeds on different road types and learns as it goes. I don't know if this applies to routing or just the ETA.

Elsinga is a Garmin Guru, maybe he knows? Robert - are you reading this?
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Gone fishing!

[Skippy]

You could also try selecting a different vehicle type in the routing options and see if the routing improves, but that may give you strange results in other area.
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Gone fishing!

[Shaolyen]

[Shaolyen]

A "pretty good pretty"?! What am I on... I meant, a "pretty good idea". ;)

[rossb]

I used to own a streetpilot III and was sometimes surprised when the unit routed me down roads not much bigger than my car.

On the relatively new streetpilot C320, there is a routing option to "avoid unpaved roads", which in theory should avoid roads like this.

Does the quest have this option?

[Shaolyen]

The Quest does have an "Avoid Unpaved Roads" option, but the problem is that these aren't unpaved roads. Unpaved roads are in my avoidances list, but it still takes me down these narrow roads.

As far as I can tell, setting the Quest to "Truck" mode makes no difference. I've uploaded a couple of example tracks here:

http://www.weavo.net/CountryRoads.gdb

This shows two tracks, from A to B and then back to A. For some reason the Quest gave a second route on the way back, which was much more difficult to drive along. Perhaps a bad example, as I was managing around 30mph on them - although I had to pull over onto the verge more than a few times.

[Skippy]

Thanks for posting the examples.

Looking at my AA road atlas I would have chosen the route via the A47 and Necton/Bradenham as the best one (presuming one would make better time on the A47) but you say the route via North Pickenham is a better! 8O

What it boils down to is that the satnav can't distinguish between the minor road types for the Necton route and the North Pickenham route. I think the road types are M, A, B, minor, residential and unpaved.

From what I can see of the tracklog, you managed a similar speed on both routes so technically speaking there isn't much to choose between them. Of course local knowledge/preference will dictate that you have a preference for one route over another, but you can't teach that to a machine unless the mapping provider categorised the minor roads into subcategories (which is unlikely to happen!).

Just be thankful you didn't buy CoPilot - it would have routed you via Dereham.
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Gone fishing!

[Shaolyen]

I've done some more testing, and it does seem that when the Quest is set to "Truck" mode it does make a significant difference when choosing routes. It isn't perfect, but I find myself using these narrow back roads less and less often. Thanks for the tip Skippy!

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