[Talk-ca] Meaning of lcn tag - designated route, or any cycling infrastructure

OSM Volunteer stevea steveaOSM at softworkers.com
Sun Feb 4 20:22:45 UTC 2018

On Feb 4, 2018, at 7:47 AM, Mike Boos <mike.boos at gmail.com> wrote:
> I've noticed some users have begun tagging some roads in a number of Canadian cities with lcn=yes tags, which are intended for marking local cycling routes. My understanding of the lcn tag was that it was intended for marking designated routes, not just any old way that is potentially bikeable or personal preferences cycling routes.

Hi Mike:

Thanks for the heads-up about your intentions.  Yes, I agree with your characterization that lcn=yes (either directly on a way or on a route relation with ways collected together as elements) is for "designated" routes.  And that is one way to do it:  another is if you know the "level" of either federal, provincial or local) where you might tag network=ncn, rcn or lcn in a bicycle route relation.  These routes might be designated by a government (federal, provincial or local) or a "cycling group" (could be a non-profit or for-profit member organization).  And/or they might be a proposal before a government body (for example, if a set of bicycle infrastructure so tagged has a numbering protocol which organizes that set), in which case you'd add state=proposed, then OpenCycleMap would render the route lines as dashed instead of solid.  But yes:  OSM has reached a consensus that such routes designated in our map data are not "simply personal preferences" by a single person who wishes to organize bicycle routes, whether on infrastructure tagged with bicycle-ish tags like highway=cycleway or cycleway=lane, or not.  They are either signed on the ground or perhaps published as a paper or online map by a government or bike non-profit who has organized infrastructure together as routes and publishes those.

> For many roads, the lcn tag seems redundant, since these ways are already tagged with cycleway=lane or something similar, and there is no accompanying lcn_ref tag to provide information on individual route names or numbers (if they exist). Other roads have been tagged, but have no infrastructure or signage, which suggests someone is simply marking their personal routes.

There really are two tagging schemes going on here, for different purposes:  one is tagging infrastructure (nothing to do with lcn or lcn_ref), like highway=cycleway or cycleway=lane or bicycle=yes (there are others).  The other is specifically for routes, and these include lcn (or much less commonly lcn_ref) and/or a relation with tags type=route, route=bicycle and usually a network=*cn (lcn, rcn, ncn, icn).  A newer (though established in both Canada and the USA) tag of "cycle_network" is also being applied, this helps to disambiguate specific bicycle networks which share the same network "level."

The lcn tag isn't redundant:  a way can be tagged as bicycle infrastructure (and that is one thing) independent of being part of a bicycle route.  The lcn tag is used when (USUALLY, perhaps ALWAYS or NEARLY ALWAYS) bicycle infrastructure IS part of a (local) route.  Bicycle infrastructure can be so tagged while NOT being part of a route, but the converse usually isn't true.

> I'd like to think I have some sort of expertise in what constitutes an official local cycling route in my area, having served as a member and later chair of the Kitchener Cycling and Trails Advisory Committee for several years. There are some signed routes that myself and others in the area have properly marked with relations. But is my understanding of what the lcn tag is for wrong? I'd like to know before I start cleaning things up.

I would strongly agree with you that signed-on-the-ground routes (almost always part of a "network") should be mapped in OSM and that "casual" or "personal" routes should not be mapped in OSM.  Again, an exception can be a formal proposal for a network or numbering protocol which has been introduced before a government body and is either in the process of being approved or implemented.  For example, routes in the USBRS, USA's national bicycle routing network / ncn have been emerging over the last several years and will take many more years to complete as the network gets "built out".

In the interests of gaining a solid understanding of this (and to "keep your sanity!" while learning), I recommend that you FIRST "get infrastructure tagging correct" on the ways which are actually bicycle infrastructure:  highway=cycleway, cycleway=lane, and so on.  SECOND, assemble these bicycle infrastructure elements into route relations (type=route, route=bicycle, network=lcn/rcn/ncn/icn).  I speak from deep experience:  sticking to that ordering, while not required, really helps.  Take your time (over weeks) and watch Cycle Map layer render infrastructure tags a certain way and route relations in a certain way.  I'm not saying "tag for the renderer," I am saying "tag correctly (by what our wiki says) and you'll get great results rendered."

Please take a look at these wiki pages of ours:

https://wiki.osm.org/wiki/Cycle_routes (the definitive guide to routing, but not infrastructure)
https://wiki.osm.org/wiki/United_States/Bicycle_Networks (how the USA assigns routes to the various levels of national, regional, local)
https://wiki.osm.org/wiki/WikiProject_U.S._Bicycle_Route_System (the specific example of how far along the USA is in implementing its national cycleway network)
https://wiki.osm.org/wiki/Key:cycle_network (has a section both for Canada and USA)
https://wiki.osm.org/wiki/WikiProject_Canada#Trans_Canada_Trail (brief, but local)
https://wiki.osm.org/wiki/FR:Route_verte (in French, but how one province implements a regional cycleway network's routes in OSM)

In the latter, especially note the table near the end after "Voici les attributs recommendés les segments associés à chacun des types:"  It shows how all member elements of the routes have specific infrastructure tags for bicycles.  That's right!

If Canada would like to create a https://wiki.osm.org/wiki/Canada/Bicycle_Networks wiki, I'd be delighted to help.

Asking questions is great, I hope I have provided you with some answers.


More information about the Talk-ca mailing list