This is a model of a four sided traffic signal light.
This scene was built in Maya 2010 and rendered using Mental Ray. Lighting was achieved using an image applied to Mental Ray's Image based lighting node then rendered with Mental Ray Final Gather. Simple environment map included. This is not an HDRI image. Not all UVs have been laid out.
The model is parented to a control curve. This curve, trafficLightCTRL, contains two custom attributes, Smooth 0 to 2 and another called Smooth Lenses 0 to 2. These attributes allow the lenses to be smoothed at different settings than the other geometry, if needed. Renders were done with the first setting set to 2 while the lenses were set to 1.
There are two groups of fill lights. Intensities for each group can be set using intensity attributes of these two lights: