My father had a post card that looked something like this sketch. It has always been in the back of my mind to attempt building these tunnels under the East River so they would each hold one subway car and maybe stick out one from the fascia of my layout.
I am thinking that PVC pipe for the tunnels, some wood or foam to make the catwalks, and strips of LEDs for the lighting. Overall, each PVC tube would be 12" long and 5" in diameter. The solid rails would be pulled from a piece of MTH Real Trax.
Perhaps more ambitious would be to cut Rail King unpowered subway cars in half, so only two cars would be necessary. The length of each car segment could be different to simulate cars deeper into the tunnels.
Has anyone tried something like this or am I pioneering here?