Hi Felix,

if your style interprets a tag like a oneway=yes you should add
that tag. This might prevent problems caused by the RoadMerger,
which might reverse lines which are not oneways.
If you find or set oneway=-1, the current implementation
will reverse the way.
If you add multiple routable lines for one OSM
way, one with, one without the oneway tag,
you will see unpredictable directions if such a way
is modified by the WrongAngleFixer and the type
is direction dependent.
The WrongAngleFixer assumes that the points in
all ways with the same OSM id are equal, so
it optimizes one way and copies the points to the others.
This will fail if they have different oneway attributes.
If you think this could be the cause of the problem,
I should be able to provide a fix.

Gerd