The NYNEX Corporation invests hundreds of millions of dollars each year to enhance the telecommunications services provided to its customers. Extensive planning and construction are required to meet the ever-increasing demand for better service and provide the latest in sophisticated equipment throughout the telephone network. Engineering groups plan changes to network facilities five years ahead, with constant adjustments for changes to forecasted service demand, changes in the economy, changes to NYNEX company policies, or the availability of new technologies. Arachne is an expert system that automates interoffice facilities (IOF) network planning in New England Telephone and New York Telephone, NYNEX subsidiaries. arachne was deployed for planning the IOF networks in the New York City metropolitan area and most of New England. It dramatically reduced the overall planning time and improved the quality of the network plans. In its first production run, it identified potential capital savings of over $10 million in Massachusetts alone through expense avoidance and capital recovery.