The tunnel entrances of the train track are made of Studio-95 products (version for E-locomotives).
The tunnel portals of the street in the front of the track are the versions for diesel / steam locomotives. These are built deeper into the landscape.
The tunnel portal on the cobblestone road is of unknown origin, I think something of scale O.
We made molds to finish the inside of the tunnels. The original wall is one that consists of pasted loose stones. When the plaster is poured, a few compresses are applied at the end, so that they make a kind of reinforcement so that the wall does not break as quickly.
To allow the curvature in the tunnel, every 2 rows of bricks fine cuts are made into the joints with a fine saw. This allows the wall to be placed in a curve. Later the joints are then backfilled with a mixture of gray tile grout and wood glue.
First, the walls of the tunnels are formed from low-expansion PUR foam. The walls are then glued against this PUR with acrylic paste. To keep them in place until the paste dries, I made accessory tools (light blue on the photo) to keep the walls in place