Use 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.