2D wireframe view showing the ribs inside each arch section as orange. At the ends of each arch section is a triangle. If you look for the triangles, you can see the top keystone piece, twice as wide as other arch segments, flanked by two smaller sections on either side. Each 1/3rd arch length, 116" deep, is made up of these five interconnecting arch segments. They too are tied together using ~1" diameter composite tubing that thread through pre holed slots in the ribs or end caps.