Welcome mate
And in addition to what Marty and Brian have suggested, the grass in the centre of the track/road could be accentuated by being on raised dirt, leaving the ' wheel grooves' to each side (Maybe too late! Future dio perhaps;)
As for the bridge, it looks great but I think that a timber finish would set the scene better. Ignore me if that is just an undercoat... :-) I like
the groundwork also, but think the longer brown grass stems should all be in the creek and its' banks, not up at ground level.
Keep the good work chooglin'!
Cheers
Brad