This is a former SCL (Seaboard Coast Line) searchlight signal in Lineville AL, with a rare doll post.
The signal is for the mainline to the left. The doll post is for the siding to the right, which is controlled by the dwarf
signal at ground level. I wish the doll post lamp was lit, because
they are of this beautiful deep blue color, cobalt blue for most of us,
except for those railfans who want to call it AAR blue (which tells 90% of
us nothing about what it really looks like! :-)
As of 2014, it appears that CSX has double tracked more of the line heading NW out of Lineville,
so this signal is no longer needed or there :-( .
In fact, it looks like everything in the picture
is no longer there! I base this on the fact that the building pointed to by the yellow arrow
appears to be the one in John's photo. The green arrow points to approximate location where this signal used to be.
The two photos are courtesy John Higginson.
Here's a picture of a signal in Waltham MA that used a doll post, but it too, is no longer around....
they did some sort of realignment and did away with the signal.