Doubly regular digraphs and symmetric designs

If an incidence matrix N of a symmetric design is such that N+Nt is a (0,1) matrix, then N is an adjacency matrix of a doubly regular asymmetric digraph, and vice versa. We construct several parametrically new infinite families of such digraphs. To carry on some of these constructions, we obtain an infinite family of skew balanced generalized weighing matrices.