No 'avoid highway' on etrex

Posted by Chaos99 on 23 July 2010 in English (English)

Last time I went for a ride on my bike (that's the loud one, not the one with pedals) although I know the aera quite well I let my eTrex Legend do some routing.

I wanted to take some arbitrary scenic route, so I switched the 'avoid highways' (don't know if it is translated that way by garmin) option on in my routing settings.

Guess where it tries to direct me? Straight to the nearest Autobahn.

So does anybody know if this is
a) a mapping failure
b) something not yet possible with mkgmap
c) a bug in mkgmap
d) a bug in computerteddys map
c) a bug in garmins routing soft-/firmware


I know there are other places to ask this and get a more technical answer, but I just wanted to check for similar experiences first.

Comment from giggls on 23 July 2010 at 08:15

You may try to use the velomap ( where the routing stuff is designed (hacked would be probably the better word) for bicycle routing..

Comment from Chaos99 on 23 July 2010 at 09:19

Thanks. Is this permanently enabled, or just when I switch to 'bicycle' as the mode of transportation on my garmin?

Nevertheless I won't make myself new friends when going with my motorbike along designated bicycle lanes and ways. It's really about using public roads for motor vehicles, but avoid big (and boringly straight) expressways.

Comment from muffu on 24 July 2010 at 09:22

For a long route Garmin seems to route by preferring the large roads (high road class in mkgmap). Near the start and finnish it has to use smaller roads as well as when the large roads are not connected. I guess Garmin uses this to make the road network smaller to make the route calculation time smaller. Putting it in other words, it seems to ignore smaller roads.

Unfortunately this means a lot of options like "avoid highways" or "shortest" are meaningless when you calculate the route for a network consisting of motorways and major roads only.

If you mark some via points for the route you can guide to smaller roads because it has to use them to reach the via point. This makes the segments shorter too ie. it uses more small roads in calculation. (More smaller roads are used for a short segment)

I've tried this with a tweaked map. I made all cycleways road class 4 in mkgmap (ie. like motorways). That map routed to cycleways (in cycling mode) perfectly. Because of the large amount of "major roads" the routing calculation time on my Oregon was useless though.

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