You will need at least 2 programs for this. A macro design program such as EOD (Easy Object Designer) to make the tunnel, and a scenery design program such as Airport 2.90 or FSSC (Flight Simulator Scenery Creator) to place it in the sim. You will still need some textures for the tunnel. You can paint your own with a paint program, or use 3rd party textures. Seems like alot for just some tunnels, but learning these programs will allow you to add MANY more objects to your flight sim world.