Our local snowmobile club has taken to mapping their routes in OSM. Their routes often lay parallel to roads, but there are instances where they use back-country trails that are 4x4/quad trails in the summer. If the Snowmobile club is trying to map out clear routes, what’s the best practice when I’m now adding in the 4x4/quad trails and end up on the same way for a section? Do I use their line and add my tags? Do I draw my own way, so they keep their clear line? Technically, they are not allowed on the road, so for any actual regular car route, this isn’t an issue. It only happens in the back-country where they are running down the middle of the snow covered/closed road in the winter.
My concern is that it could be confusing if their clean ‘green line’ is broken because it changed color for a section.
What’s best practice?
Hi. I believe it’s discouraged to have multiple overlapping “highway=xxx” ways. So where your sled trail meets, say, a snow-covered road where sleds would be ON the road, you’d want to use just a single way for the overlapping section, with tags from both usages. Eg, highway=track, motor_vehicle=yes, snowmobile=yes, …
In the case of sled trails in the ditch beside highways (not allowed ON the road), I’d suggest drawing a parallel trail, not touching the road except where it might cross.
I wouldn’t worry about colors for any overlap sections. A road map may ignore the sled tags, while a sled map may ignore the road tags, each map doing something appropriate for their usage. 
Makes sense, thanks.
Thanks for the tag examples. I never would have thought of tagging it that way.
Where does a person go to learn how to tag properly?
The wiki is the standard go-to for tagging, eg
https://wiki.openstreetmap.org/wiki/Key:highway
…with local guidelines:
https://wiki.openstreetmap.org/wiki/Canadian_tagging_guidelines
When it comes to logging roads, track vs unclassified vs tertiary, it’s a bit of a grey area; there’s some room for judgement. I explained my reasoning in this thread:
https://forum.openstreetmap.org/viewtopic.php?id=64977