A parallel buffer is represented as one block with only one row and the required number of columns for each parallel buffer slot. That means the block has a separate section for each buffer. Parallel buffers are defined in the Stack Block form (on page 1) by using a Block Type of Parallel Buffer.
For your parallel buffer block, you must define the paths used to access that block by specifying the respective ingress and egress vertices, even if they are the same vertex. If an ingress vertex is missing for a PB or block with only one row, N4 uses the egress vertex instead for distance calculations.
The yard path model requires a path:
Between each parallel buffer (block section) and the adjacent buffers.
From each bollard to the closest parallel buffer.
From each waterside transfer zone (WSTZ) to the closest parallel buffer.
Figure: Required paths for a parallel buffer