Thanks for the great mod! Now we can build proper roads & highways, and have a great driving experience in Factorio!

May I ask for some extra tile types, like a L-shape (90 degree turn) or T-shape tiles? They would be great in constructing direction arrows in road markings. (Reference: http://www.adcidl.com/pdf/Germany-Road-Marking.pdf)
Here is another picture denoting typical direction arrows used, as number 8 in the picture http://www.gettingaroundgermany.info/g_imgs/markierung2.gif

Thanks in advance.

Sorry to revive this thread. But I wish to draw some attention to the author.
After settling your mods in migrating to 0.17, can you consider this idea, and the Fitting diagonal line glitch?

Hi Schallfalke, i'll consider it for sure. But adding new tiles will need some sort of "tile management", since Factorio only supports not more than 255 different tile prototypes.
Regarding the diagonal line glitch: Unfortunately, there is currently no workaround, because the diagonal lines are placed one layer above basic asphalt in order to use tile transition graphics for displaying the small bits between the tiles, thus forming a continuously line. This means that tiles with diagonal lines are completely independent from other asphalt tiles.

Thanks for explanation. No rush, take your time to think of a good solution.

Regarding the tile restriction, there is an idea pop up in my mind. Don't know if it maybe useful to you or not.
The idea is to use entity for at least some of the markings. See in my Schall Lamp Contrast mod, I altered the vanilla lamp with different collision layer, so vehicles can safely drive over the lamps.
By this way, players place the asphalt tile first. Then "paint" the tile with markings "entity" over the tile.