Surfaces on Stratis are incorrectly mapped. This leads to AI unable to stay on roads and it seems roads are labeled as just dirt, that same with runways too are incorrectly labeled.
Objects which are currently correctly labeled appear to be metal buildings only.
The casings or bullet class only has 4 sounds defined for each class of surface :/ so basic its hard to mistake the findings.
A simple way to test this is to take a weapon with casings ie EBR, Zafir etc and fire it on the runway and see which sounds occur (gives grass sound) try on roads also try dirt etc.
Agree with the road mapping as currently working on Convoy missions within the Stratis map. The AIs behaviors are set correctly according to the Biki and seem to find it nigh on impossible to use the roads?