this is not a block signal

this is not a block signal but probably a stop board for a diamond . Block signals (also known as Automatics ) are fully automated showing track condition ahead (occupied or not ) . Most signals do not indicate route only speed , some western roads do use signals that indicate a diverging route. the signal you show is called a stop board. the crew would stop look both ways on the other railroads tracks and if all was clear move the board to favor their movement.  It would stay in that position until the next train arrived on the opposing line unless directed by timetable to reset it after passing.  hope this helps railroad signally is not as simple as we model railroaders think it is.

Signal

rickrubino: Thanks for the info on stop boards. It is probably accurate, But on my pike I use it as shown, no insult to you. Thanks, Elvin Howland/E. St. Louis Rail Group Layout.

Most people would think

people who work on railroads, are simple folk.  But signaling is no simple matter! 

individuals who take a shot

individuals who take a shot at railways, are basic people. Be that as it may, flagging is no straightforward matter!

Train On Branch

The Reading Co. had a similar signal, it was called a "Train on branch" signal.  When a train went on the branch, they would set the signal to stop, any train enter the branch after that had to proceed under flag protection.