Cut your center block 4 1/2" and use 2" strips. That should come out to a 12 1/2" block.
After sewing your strips d,l,d and l,d,l cut them in 2" strips and sew them back together to make the 9 patches
Sew l, d, l strips and cut at 4 1/2" to make the rails.
Your sashing can be any size you want although it appears to be 4 1/2" in the picture.
This might be a version of Cornerstones and Rails block.