Tunnel Portals, Retaining Walls, Culverts, and Roads reinforce natural terrain contours and add functionality, realism and interest to your layout! ~ Add a concrete tunnel portal over any HO scale track. ~ Color with Earth Colors Liquid Pigments. Outside: 5 3/8″w x 4 7/8″h – Inside: 2 11/16″w x 3 11/16″h.







