Thank you for the respond.
Sand road doesn't look much different I think, here in my area sand roads don't have grass in the middle, the middle generally a bit lighter colour from erosion.
The roads I was thinking of when drawing this, usually have only one lane and run e.g. between fields to remote farms or settlements. These roads are usually only drivable by tractors or offroad vehicles, and not fixated like normal roads. But one-lane roads in OTTD are not supported, so I made two lanes.
If you want real sandy roads you might want to use the dirt road of Unspooled (or ARRS for non-NRT games).
But I might come back to your suggestion for temperate climate, as it looks a bit off with greenish grass in between.
Is it possible to have a road type effect reliability of vehicles driving on it?
I thought about implementing a different usability for normal RVs and heavy hauling trucks myself. But I think such things are not possible to implement road type-wise.
Also, this should eventually be done via RV sets, I think.
(Though, as the standard speed limit is 20 km/h, the player might feel like RVs break down more often, as it takes quite some time running over long roads
What I'm looking into implementing is changing the speed limit due to snow. Such roads aren't usually serviced so they should become quite a hassle in winter.