Abstract: An autonomous controller includes a microprocessor, a programmable memory for storing a plurality of cycle structures, a clock/calendar circuit accurate to within a few seconds per month, a lamp driver including a plurality of isolated outputs for operating traffic signals, a display driver for providing a indication of optimum speed through the controlled intersection, and an I/O device coupled between the microprocessor and an external connector for downloading the cycle structures to the programmable memory. The microprocessor reads data from the programmable memory, selects a cycle structure suitable for the time of day, and causes the lamp driver to control the traffic signals in an intersection in accordance with the selected cycle structure.