Recommendations

When basing your model on the original ones, add to your mod also ALL original /automat/ files used by it. The names of the files are generated as CityHash64 hash of theirs content so whenever we change the parameters of the material in any way, a different file will be used to store them and the original file might cease to exist if there is no other model utilizing the original parameters.
When modifying original models, always include ALL components of the model (pmg+pmd) instead of just those you changed. Otherwise you risk crash if we change the model.
As always when adding new objects to files which support multi-file approach (e.g. road_look.sii) it is HIGHLY RECOMMENDED to use suffix or prefix in the name to avoid conflicts with new objects we are adding in patches. Otherwise you might have to use the batch renaming functionality (see Batch renaming) to fix the conflicts when new patch appears.

How to convert map

Ensure that ALL map files are updated to version compatible with 1.30 update by resaving them in 1.30 version. Otherwise you will be unable to load the map in 1.31 editor.
Load map
If the editor shows a warning dialog about items referencing obsolete TERRAIN ONLY road flag, you MUST remove or replace all those items in the map before saving the map. Otherwise the editor might crash when loading the resaved map.
Run prefab node corrections (F3 - "Prefab node correction")
Save map
Do rebuild (F8)
Save map

TODO