Major navigation issues with Garmin 1030 and 820 devices

Don’t forget, the OSM data is just the raw data. What Garmin does with this and how it interprets and translates this into its Cycle Maps is not known to us.  They may chose to override the access=* tags and replace them with something else based on the category of the highway. Unfortunately Garmin won’t tell us what they do. Other compilers of OSM data like OpenTopo or OpenFiets may honour the raw data more faithfully and hence why you get different results with different maps despite the routing engine staying the same. 

I wish we could get that out of Garmin so that everyone could understand what is going on and help make a better product for everyone concerned. 

Your knowledge of OSM mapping is far superior to mine. I wouldn't know where to begin finding, which roads are given OSM Trunk classification. The only road near me, which I know has this classification is the A595 & only 30Km of it's 140Km length has officially got trunk road status as designated by the Highways Agency.

Although I do know that the edge routing does take issue with highway:primary roads too as another road the A5086 has this classification & the edge makes every attempt to avoid it like the plague

"Don’t forget, the OSM data is just the raw data. What Garmin does with this and how it interprets and translates this into its Cycle Maps is not known to us."

Yes. That's why the OSM defaults are irrelevant.

It's not "more faithfully". It's just different.

Being "faithful" to the irrelevant OSM default would be a real mess in the US.

There isn't any indication that Garmin ignores the access tags (there is no reason to do that). I've updated the access tags in OSM and had them reflected in the Garmin maps.

The problem is that the A roads don't have access tags making cycling-allowed explicit.

Some of the openfiets maps defined cycleways as Garmin "highways" so that older units would prefer them in routing when automobile routing was used.

If it helps any I have tried to generate courses/routes in Connect as well as RWGPS.  Typically the course generator will not let me route onto what in the US is the interstate system (UK equiv.to the M roads), nor what is locally known as "Parkways" that are cars only, no bikes, commercial traffic, trailers, etc...  Connect has a selection for "Other" as a choice of "vehicle (I.E. road, mountain. gravel, hiking) but will not navigate on a road closed to bikes.  Neither will RWGPS, using either the Google map or the OSM cycle map, unless I tell RWGPS I am driving.  Then it works.  So you might try Driving as an option, possibly the actual device won't know.  

It helps to find stuff on maps if you mention the nearby city.

"The only road near me, which I know has this classification is the A595 & only 30Km of it's 140Km length has officially got trunk road status as designated by the Highways Agency."

What matters is what OSM says. OSM tries to apply a "universal" definition for terms. Those definitions might not match the local usage/application.

The A595, which runs from Grizebeck (south) to Aikbank (north) is a trunk road in its entirety in OSM.

Note that roundabouts on trunk roads are also designated as trunk roads. That means the Garmin won't route across them at the trunk roundabout.

A5086 is indicated as a primary road for its length.

I looked at what happens with maps from http://garmin.openstreetmap.nl/ in Garmin BaseCamp.

BaseCamp uses the Garmin map format and appears to match the routing behavior on the Edges fairly closely.

By default, the "bicycling" routing profile in BaseCamp excludes major highways. 

• In the "generic routable" map, A5086 is classified as a "major highway".
• In the "openfiets" map, A5086 is NOT classified as a "major highway". 

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You can go on the OSM site. Motorways are kind of dark pink. Trunks are dark orange. Primary roads are light orange.

Here's an illustration:

www.openstreetmap.org/

M271 at the north is a motorway (dark pink).

A33 at the east is a trunk road. (dark orange).

A35 at the west is a primary road (light orange).

Thanks for taking the time to have a look at this & pointing me to where I can find the classification information in future.

I've been using the generic routable maps from openstreetmap.nl as my 3rd party maps & accepted that bicycle routing may yield similar results as the Garmin maps. They do however allow me to use Automobile or motorcycle Routing when needed, which gives much more realistic routing with respect to using major highways & trunk roads to provide a more direct route to a destination.

I haven't tried the openfiets maps yet but will do some testing with those and see how the routes compare using different routing modes thanks for that info

Most sections of the A595 have been gradually de-trunked over a number of years since 2003, with only the 30Km section between 2 places called Chapel Brow & Calderbridge still retaining this classification. I guess this just goes to highlight how the OSM classifications might not necessarily match the official classification held by that road 

"I guess this just goes to highlight how the OSM classifications might not necessarily match the official classification held by that road."

It's important to understand that they aren't the same thing. They are somewhat related but they aren't the same thing.

In any case, the only thing the Garmin "knows" is what's in the map. Talking about information in other places is actually irrelevant. It's likely you'll just confuse yourself or other people talking about information in places other than the map.

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It looks like Garmin compiles their maps with treating all A roads as "main highways".

I think they should actually use the road classification. 

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I'm a fairly active OSM editor (I've fixed issues all around the world).

I also have compiled maps (so, I have some idea how that works).

(It's almost certain that Garmin is using the open-source compiler everybody uses.)

"A" roads in the UK are still a problem.

It appears they are all treated as "major highways" though only some are indicated as "trunk" and others as "primary" in OSM.

That means the routing on the Edges will produce goofy long-way routes to avoid using them.

The roundabouts should probably be classified as non-major-highways so routes can at least cross the A roads.

I downloaded both the Generic Routable (new style) & Routable Bicycle (Openfietsmap Lite) maps of the UK from openstreetmap.nl on to my edge & performed some tests; picking a route between two points that I would expect to use the (A595/A5086) trunk & major highways mentioned in my previous posts. I was using the Bicycle Riding routing mode with only Unpaved Roads set in the avoidance settings.

When calculated; the routes from both maps used the above roads as I would have expected them to. The only strange thing was when I was trying different avoidance settings and set them to avoid Toll Roads. With that set; for some strange reason when using the Routable Bicycle (Openfietsmap Lite) map the calculated route would avoid the A595 Trunk Road, which left me somewhat confused as to the cause as I don't think there's any reason for it to be tagged as a toll road in the OSM map