US Patent 7808402 Multi-mode traffic signal bulb assembly

Systems and methods of controlling traffic including a traffic signal. The traffic signal including one or more lamps configured to each display a plurality of patterns by selectively powering different groups of bulbs. Embodiments of the invention include lamps configured to alternatively display an arrow pattern, a filled circle pattern, a bar pattern or other pattern meaningful to traffic control. The pattern displayed is optionally dependant on available power sources, ambient light, traffic flow, time of day or day of week. Embodiments of the invention include a bulb assembly including different groups of bulbs and configured to be controlled using as few as two hot electrical inputs.