PORSCH:

I found that great map at the FEEFHS The Federation of East European Family History Societies.

Helmut Porsch and his Ancestors were from Dirschau, Danzig. A later record shows his father Julius as a Zugferer. As Dirschau was a major railroad connection perhaps that is what he did there.

The link is http://www.feefhs.org/maplibrary/german/ge-wprus.html