I took photos of the molds used for the relief designs to be placed on the 3300 South bridge. The process is simple. They make styrofoam cut outs and paste them in the concrete mold for the bridge abutments. The workers then pour in the concrete (as you would any mold). Let it dry. After pulling off the mold they remove the styrofoam, sand blast and they have a simple relief picture.
I am happy that construction crews have started adding art to bridges.
The ancient greeks used to stick bas relief sculptures on everything. I guess you could make those by having people stick their face in plaster. The a mold from the facial indent.
Hmmmmm, if they need a model for an Adonis, I guess I could lend my chiseled visage. Of course I wouldn't want them to use my face for highway work as I would worry about all of the ladies becoming distracted while they drive by.