First, the tunnel portals. I used styrene stone texture sheets with plain, white, 1mm X 3mm styrene braces for the entrance.
Oh! by this time I also took the liberty of doing some ballasting. :P
Coming back to the tunnel, I then added the retaining walls...
Then the paper mache and the road... This road is going to lead to the Lighthouse. It's a thin service road to handle small and medium vehicles, with very tight clearance for vehicles going in opposite directions. Honestly, I personally would never likely drive, or even ride a car on that piece of @#$*&!