Dual control switch operating instructions shop sign

Hi, I'm not sure if I'm in the right place but wasn't sure where to go with this. It is a framed paper sheet with instructions on how to operate what appears to be some sort of telegraphic signaling switch related to railroading. It mentions "the operator in Marion, Iowa." It is signed LB Porter Supt. telegraph and signals. It is a copy, but I'm not sure if it is a company issued original or a copy of one. It's an interesting piece but I am unsure of what it's about and possible age. Thanks ahead for any thoughts or ideas.

 

A Google search will bring up information on L. B. Porter. Appears to have assumed the superintendent role sometime in the 1940s.

https://www.jonroma.net/media/signaling/railway-signaling/1947/Developments in Signaling.pdf

Debora

 

This is the guy ...
https://www.google.com/search?q="l+...160l4.49432j0j7&sourceid=chrome&ie=UTF-8#ip=1

 

Thank you, I think for some reason I searched for RB Porter. And I was thinking it was a little older than this, but seeing that info it fits. Not that I understand much of it.

 

Yes, I used incorrect initials somehow. It seems he was definitely the go to guy in this area. Thanks for the lead.

 

Great old communications piece-& a double /triple collectible,telegraph,RR,etc.