I actually found a picture of the kind of Chicago Parks ESSCO signal that I was looking for information about:Image Information:
Title	Traffic Intersection at Central Blvd and Jackson Blvd (image 05)
Creator	Chicago Park District Traffic Section
Subject	Traffic Intersections
Date of Original	June 3, 1937
Time Taken	10:45 AM
Geographic Location Central Avenue + Jackson BoulevardLatitude	41.876508
Longitude	-87.764714
Direction	0
Type	Image
Form	Photographs
Physical Description	Film Negatives
Format Digital	image/jpeg
Source	Illinois Department of Transportation Chicago Traffic photographs
Collection	IDOT Chicago Traffic Photographs (University of Illinois at Chicago)
Repository	Special Collections and University Archives, University of Illinois at Chicago Library
Host	University of Illinois. Library.
Rights	This image may be used freely, with attribution, for research, study and educational purposes. For permission to publish, distribute, or use this image for any other purpose, please contact Special Collections and University Archives, University of Illinois at Chicago Library, 801 S. Morgan St., Chicago, IL 60607. Phone: (312) 996-2742; email: 
lib-permissions@uic.edu.
Citation	[identifier], Illinois Department of Transportation Chicago Traffic photographs, Department of Special Collections, The University Library, The University of Illinois at Chicago
Identifier	IDOT_2f_65_5705_37
Picture of signal --
http://collections.carli.illinois.edu/c ... x=57&y=110Wider angle picture of intersection,  that's under construction - with signal in foreground --
http://collections.carli.illinois.edu/c ... DMROTATE=0Closeup of area in the back of the same picture of this this intersection, that's under construction -- 
with view of Chicago Parks ESSCO signal actually being installed -- and truck full of them ready to be installed - WOW! --   
 http://collections.carli.illinois.edu/c ... &x=94&y=47
 http://collections.carli.illinois.edu/c ... &x=94&y=47