It is possible to make many compatible radii using a combination of Radius and small straights as follows:KAT-20-150 (28 1/4") Radius , KAT-20-160 (19") Radius 15º , KAT-20-140 (15") Radius 30º , and KAT-20-091 Short Track Assortment 29mm (1 1/8") [8 pcs], 45.5mm (1 3/4") [2 pcs]The following Picture shows how to arrange the pieces