Hi again. Brano...
I'm glad to see interest in the set of Tools... because Tools are the most valuable thing for a terrain engine.
In WWIIOnline, the old set of terrain tools, was a big problem for years... consuming a lot of man hours.
Your Road Tool are really good... but i'm here to make a proposal with fresh ideas.
If this engine it's aiming to simulators at planetary scale... the option for editing roads, is a good element to fine tune road placement in those points that the automatical placement failed.
But for a planetary scale engine, is imposible for a developer to do all the roads one by one without some degree of automatical placement of roads.
For example... if You can use some of the Old Road Maps of Europe like those ones as imput:
http://www.lib.utexas.edu/maps/ams/france/txu-oclc-6617501-nm30-9-cop.2.jpghttp://www.lib.utexas.edu/maps/ams/france/You will be able to deploy an initial road map very close to the roads that you can find in europe by World War 2.
The automatic tool needs to know the latitude and longitude of each corner of the map, and the color of the lines that are user in the map to mark roads... also with the definition of the class of road (features).
If it's posible to build that kind of tool... this engine will be really usable for many games... because if you want a WWII era simulator, you only need to find the maps of those years... and if you want a cold war simulator... then go for the maps in that era.
It will be even possible to find roads of the Roman Empire... so your engine will be open to almost unlimited posibilities.
The conection between roads and City streets, can be done by hand with a manual tool... this work can be done in a manual fashion... but the road map of europe by WWII for example, will be possible only if you build some kind of automatic tool for road generation.
Man hours in a game development, count a lot... all the tools need to be usefull enought to limit the number of works in man hours.
Regards from Spain.