On 13/06/19 18:41, Tobias Zwick wrote:
Here, legally, if there are no lane makings then it is considered to have one
lane in either direction.
I am kind of a fan of lanes=0, denoting that there are no marked lanes. Here is
why:
a. if a road with no lane marking is tagged as lanes=2, this situation cannot
be distinguished from a road with 2 lanes
b. if a road with no lane marking is tagged as lanes=1, this situation cannot
be distinguished from a road with 1 marked lane (a oneway road?)
So, in both these cases, the tagging is not explicit.
But it is important to be able to make the distinction. Some reasons:
1. Verifiability: Clearly, "on the ground", a road with 2 lanes looks different
from a road with no lanes. A famous example for even a very broad road that has no lanes
is Place Charles-de-Gaulle in Paris [1]
2. Legal implications: As far as I know, there are legal implications for roads
with no lanes. Depends on the country of course, two examples that come to my
mind:
2.1 In Germany, (afaik) it has implications when passing obstacles. If there are
marked lanes, you can only cross into the other lane when it is free, while if there are
no marked lanes, whoever reaches the obstacle first may pass first, independent on whose
"side" it is
2.2 In China, the default speed limit if nothing is signed in towns is 50
km/h but on urban roads without a center line, it's 30 km/h [2]
3. Fuzzy/Implicit implications: Software may want to treat roads with unmarked
lanes differently from ones that are marked. A few examples:
3.1 StreetComplete may want to ask surveyors to measure a road width in
meters only for unmarked roads because they are likely very thin and the
traffic throughput is not clear through the lane count
3.2 router software may want to slightly prefer roads with lanes>=2 over
unmarked roads and/or calculate a virtual lane count from the given width, if any
- especially if the maxspeed-tag is missing
3.3 map rendering software may want to render roads as they appear in
reality. F4Map already does this rudimentary [3]
---
Now, my argumentation is in favour of making a distinction between unmarked and marked
but not explicitly for lanes=0. I wouldn't mind or even slightly favor a tag like
nolanes=yes or similar - this would be even more explicit. But since this does not exist
(yet), lanes=0 would do as well in my opinion because it also reads as "zero (=no)
lanes".
I think a tag to say "lane:marking=no" could be better for that situation???
lanes=* says the number of lanes, it does not say if they are marked or
unmarked as demonstrated above.
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