The transformation of five traffic signal control boxes or “invisible canvases” around the Northeast Corridor is intended to promote pride and unite the community in the area. These boxes are collectively called The Big Picture Project, a public art initiative that uses the gateways of the community to share the stories of the neighborhood.

In 1821, Hiram Bacon settled in Indianapolis and as time went on the barn that was on his property served as a station in the Underground Railroad. Depicted on this traffic signal control box is an escaped slave, whose shout for freedom breaks the chains around him. The orange pattern that covers the central image is known as the “monkey wrench”; this pattern was used as a code to identify a safe house.

Quoted from http://us9.campaign-archive1.com/?u=fcf86f7c3f5754fd259da4f7c&id=d8dedccfe8&e=14c2ef4487