[Tagging] tagging of one-way cycle lanes

osm.tagging at thorsten.engler.id.au osm.tagging at thorsten.engler.id.au
Fri May 11 12:25:13 UTC 2018

> From: Martin Koppenhoefer <dieterdreist at gmail.com> 
> Sent: Friday, 11 May 2018 21:45

> while I would generally agree with the idea of having officially 3 lanes, 
> I would have thought that lanes would have to be painted on the road, not 
> just indicated by signs. 

Under the strict reading of the definition on the wiki, probably. The real world is never as nice and tidy as the data models we try to make of it. The road is designed to have 2 lanes (plus a psv lane). That's made clear by the sign. That they never bothered to mark it on the road surface (or it got lost after a repaving maybe) doesn't really change that.

> If 3 vehicles drove side by side (which is the 
> typical situation there, not counting the psv lane), which one would be "outside" the lanes?

The middle one clearly, it's half way in each of the official lanes.

> while I still agree, following this concept would mean to count 
> lanes based on situations somewhere else, not? What if the lane 
> count changes between the intersections (indeed happens), where 
> would you split the highway if no lanes are painted?

In the absence of any signs that would indicate such a change, it depends on the width of the road.

If the number of marked lanes at the intersections differs, it's very likely that the width of the road will also be different. 

In that case, if there is a clear point where the width of the road changes, that's the split point.

If the chance is gradual, take the midway point.

If there is no noticeable change in the width of the road, assume the number of lanes in traffic flow direction remains constant up to the point where it clearly is indicated by road markings to be different.

Assuming you have high enough resolution imagery, use JOSM and the "lane and road attributes" mapstyle, then specify your lane widths in detail using width:lanes at the points where the lanes are clearly marked. 

Adjust the geometry of the way to try and fit it into the available road surface along its way. Then work outwards in both directions from the points where you know the lane count for sure based on road markings, you will clearly see if there are places where you need to increase or decrease the lane widths. 

If you need to decrease the land width below about 2.5m to make it fit, that's a strong indication that you have too many lanes from that point on. If you have to increase the land width much beyond 3-3.5m, AND further down the road are more lanes than you currently have, it's probably time to increase the lane count.

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