Great transitional 15-4 double step prism

The great transitional 15-4 double step prism is a convex isogonal polychoron that consists of 30 bilaterally-symmetric digonal scalenohedron, 15 rhombic disphenoids, 90 phyllic disphenoids of three kinds and 60 irregular tetrahedra obtained as the convex hull of two orthogonal 15-4 step prisms.

The ratio between the longest and shortest edges is 1:a, where a is approximately $$3.4786372275191922766883826$$.