Exporting mesh roads as .dae?

Hello!
Is there a way to export a mesh road as a .dae file, or anything that can be opened in a 3D sofware? I'm planning to make sidewalks by using mesh roads. The problem is that i want to add a small grass island between the curb and the actual sidewalk, but as far as I know, there is no way to add ground model to the mesh road and therefore the grassy part of it can't act as grass. It's not that big of a deal, but would be nice since it adds a little bit of detail to the road.
It would be also easier to fine tune the sidewalk in a 3D editing software and export it back to the game as a static object.
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Also, is there a way to add ground cover to work wiht a texture placed on a 3d model?