Real-time traffic signal optimization software was developed using object-oriented techniques based upon the SPPORT (Signal Priority Procedure for Optimization in Real Time) model. SPPORT is a rule-based model that provides specialized mechanisms for transit priority. Based upon a flexible discrete-event traffic simulator that realistically models the effects of transit operations on the general flow of traffic, and equipped with rules designed to provide effective transit priority while still giving appropriate consideration to other traffic, SPPORT generates signal timings to minimize an objective function in which transit vehicles may be weighted as deemed appropriate in relation to other traffic. In developing this software, the SPPORT model was extended to support user-defined intersection configurations, multiphase traffic signal operation, and a more advanced form of transit priority that considers both nearside and mid-block transit stop locations. The fundamental concepts of the SPPORT model and their relationships to the key components of the SPPORT software are the foci of this paper. An illustrative example and a set of simulation test results are also presented.