I started working on the ridge structure that will eventually support the ground surface.

First, I cut out piece of cardboard that would fit between the road and the ridge corner. I cut out a hole for the track opening. I also cut out the shape of the ridge. I hot glued it at forty five degrees off the vertical walls.

I cut out and hot glued a vertical piece between the vertical wall and the piece just added. I hot glued it to the back base piece. This will add more structural support to the corner.

I continued adding vertical pieces. I cut out holes to fit around the track. I cut out the ridge shape. I hot glued them to as many surfaces as possible to add structural support.

I added pieces around the tunnel. I carefully hot glued the inside of the front vertical piece to the back piece to form a clean corner.

I added vertical triangular cardboard pieces next to the tunnel portal. I will attach custom styrene abutments to these later. I added some other pieces that will provide places to attach horizontal cardboard strips to later.

I will continue to add vertical pieces to the rest of the mountain ridge.