Thanks Gerd, So if I understand it right, technically it is not impossible, only mkgmap is not ready for this, right? Thats no problem, since the traffic sign tags are still experimental phase too.
the tag traffic_sign=* is ignored by the link-pois-to-ways option, so the first problem is that no POI is created for this node, and you can't change that in the style, because the processing happens before style rules are processed.
If we would change that somethow, the 2nd problem would be the direction. The current implementation in trunk creates short way with the access restrictions, and it would be quite complicated to change that so that e.g. two oneways are created, one with a restiriction, the other without.
In the high-prec-branch this looks easier, as it creates a route restriction for each direction by default. We would just need an additional tag to tell mkgmap that only one direction is needed.
Gerd