A good mapper can fix traffic issues 99% of the time, I'd reckon saying 'the mapper can always fix traffic mistakes' isn't too far from being 100% true. The tool picks one-way or two-way traffic depending on the decal road's properties, the lane amount set, and if one-way is checked or not in the properties of the decal road. That's a mapper's duty to set these things right, or in the case of older pre-0.9.0 maps (or somewhere around there!), the maps might not have it. All roads on OLD maps are two-way. Would be neat to have the 'Race Track' functionality, though. If the roads are set right on a race course that only goes one way, it shouldn't be too difficult. Currently, vehicles only travel the WRONG direction on one-ways if there are not enough nodes on the decal road (you may still see this in Roane County over long bridges for example, I can't really fix that at this point). As-per Roane County, @Gamergull I will have a beta to you in just a few more days ... latest Tuesday-Wednesday or so. It should hit BeamNG servers Friday~Monday a week from now or whenever the mods get around to approving it once it's uploaded and tested privately and I hand the link off to the moderators. This is just a quality-of-work update for function with the traffic tool and to look better in the process (not to mention fixing a termite colony's worth of bugs).