In 1997, PNM Electric and Gas Services began development of the Transmission Asset Management and Information System (TAMIS), an Esri-based GIS for high-voltage electrical transmission lines. This application, which was presented in its basic form at the 1998 user conference in San Diego, began as a tool to assist linemen in determining routes to structures. As development of the application continued, enhancements were added to increase the functionality of other modules such as inspection, maintenance, and fault location. The purpose of this paper is to discuss the enhancements to TAMIS to substantially increase its functionality.