[Transportation] OSM access:both_ways=no wrongfully interpreted as denied access

[sokadd]

First we need to understand what access:both_ways even tries to describe. Problem is, it is not even directly documented, although the suffix :both_ways is:

The third option both_ways is used for the lane in the middle of the road that is used in both directions (e.g. a centre turn lane). This should not be used to mean "forward and backward", as this is the default meaning of all un-suffixed keys. Under certain circumstances an additional forward or backward behind both_ways is needed.

By applying this explanation to the access key, we get the understanding that highways with access:both_ways=no have a "middle"/"center turn" lane, but you are no allowed to use it.

The following OSM example shows this clearly with ways 1014909000 and 1014908999:

The corresponding Overture features are 0871faa0a8ffffff0474bfb8a7497e48 and 0861faa0afffffff0479fe40a6440659 where you can also spot the denied access_restriction.

By my understanding, the Overture data is wrong about this, because restricting access to the middle lane does not mean restricting access to the entire highway, in both directions.