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Clarification on Avoidance and Routing

Daveymorrisuk
over 5 years ago

Seeking help on clarifying how the OSM tags are used by Garmin in their routing engine and how avoidance are evaluated.

e.g. the Avoidance Settings on the Edge 1030, Road Routing Mode are:

  • Major Highways
  • Toll Roads
  • Unpaved Roads
  • Ferries
  • Narrow Trails

From an OSM perspective does anyone know what these mean?

https://wiki.openstreetmap.org/wiki/Key:highway

https://wiki.openstreetmap.org/wiki/Key:surface

  • Major Highways - Is this anything Motorway and Trunk or does this include Primary as well?
  • Toll Roads - toll=* (seems straight forward)
  • Unpaved - surface=??? What? What does Garmin count as Unpaved?  There are loads of surface tags (see above).
  • Ferries - Ok, route=ferry (I guess)
  • Narrow Trails - got me here, what the heck does that mean?  Very few roads in the OSM map have width defined (at least from what I've seen anyway).  Does this mean highway=unclassified, highway=track or highway = residential??

Thanks

Dave

  • 0 over 5 years ago in reply to Daveymorrisuk
    • "There is a difference here between preferences/avoidance's and entitlements."

    Yes, there's a difference. There's a difference between avoidances and preferences too.

    Adding "cyclists allowed" might not override the exclusion of trunk (it would depend on the rules Garmin uses to compile the map.)

    • "Narrow trails is still a mystery to me."

    "Narrow trails" is most-likely "path" on OSM. Garmin doesn't use "motorways" or "trunks" either (and that isn't a mystery to you). "Path" is what is generally used in OSM for hiking trails, which are generally not usable by normal cyclists.

    The avoidance menu is different for different "Routing Modes". If the Routing Mode is "Mountain Biking", "Narrow trails" is not in the menu. Thus, "narrow trails" are paths used by bikers.

    "Major Highways" is an avoidance option for "Road Cycling". So, select that if you want to use A roads (and motorways?).

    The "Routing Mode" should change the order/preference of what ways are selected. Mountain Biking should pick "Narrow Trails" over other ways. "Gravel Cycling" should pick "Unpaved Roads" over other ways.

    "Mixed surface" would seem to be for touring or hybrids.

    • "In terms of cycle highway use the food chain would go as follows. Motorway, trunk, primary, secondary, tertiary, unclassified, track, path."

    Motorways almost always prohibit cycling. Why should they be in the "food chain" for cycling? "Food chain" is confusing (it usually implies an order where the biggest thing is last). If you mean an order of selection (where motorway would be the first selected), many cyclists would be mad if the routing kept dropping them on motorways and trunks (at least in the US).

    • Yes, the word 'unclassified' is a historical artefact of the UK road system and does not mean that the classification is unknown.  We have loads of rural roads tagged as unclassified in the UK.

    Yes, I figured that out. I don't think it matters. I suspect that "residential", "minor", and "unclassified" (maybe, "tertiary" too) are treated the same.

    • "There is no such thing as an assumption here, just data and an algorithm to interpret it."

    That cycling is or isn't allowed is not generally in the data. It has to be assumed.

    Garmin assumes cycling is not allowed on motorways and trunks.

    That assumption works in the US but fails for trunks in the UK.