Fabrizio kind reply -
The road direction is based on the polyline orientation (I mean it depends on the way you draw the polyline). BTW if you used a grouped set of entities to create the middle line, instead of using an ArchiCAD polyline, this direction unfortunately can be random: due to the ArchiCAD way to handle the grouped entities.
Please, pay attention: once you create the Road preview the direction cannot be changed (as you already realized)......
In order to better help you, I'm going to upload a new maintenance update at
www.cigraph-store.com (please, look at the date to verify if the version has been uploaded today, I will write 9/16/04 in order to distinguish it from the previous one uploaded yesterday).