  We construct weight-preserving bijections between column strict shifted plane
partitions with one row and alternating sign trapezoids with exactly one column
in the left half that sums to $1$. Amongst other things, they relate the number
of $-1$s in the alternating sign trapezoids to certain elements in the column
strict shifted plane partitions that generalise the notion of special parts in
descending plane partitions. The advantage of these bijections is that they
include configurations with $-1$s, which is a feature that many of the
bijections in the realm of alternating sign arrays lack.
