Woodland Scenics Concrete N Scale CulvertsUse Earth Colors Liquid Pigment(tm) to detail Culverts in your choice of colors. Approximate outside dimensions: 1 3 8'w x 3 4'd x 5 8'h. About Terrain Structures Tunnel Portals, Retaining Walls, Culverts, and Roads reinforce natural terrain contours and add functionality, realism and interest to your layout. WARNING: CHOKING HAZARD SMALL PARTS! NOT INTENDED FOR CHILDREN UNDER 3.