The rapid proliferation of microcomputer software packages for netw? rk-based transportation planning, with different capabilities and h1! 1itations, makes it difficult to evaluate and select a package to satisfy te needs and constraints of a particular agency or transportat10n planner. The software selection process is complex? ecaue it involves a multi-objective decision-making process with 11!-? fmed tad_eof! s between the objectives as well as the capa-? 1ht1es ñd hm1tatons of lt_ernative packages. An expert system 1s descnbed to assist practJcmg transportation planners and engineers in selecting microcomputer packages for network-based transportation planning to satisfy their agencies' needs and constraints. The Network-Based Transportation Planning Software Selection Advisor (NETSSA) is implemented in LISP on a VAX computer. NETSSA is highly interactive and user friendly. Its current knowledge base includes nine software packages· however, it can easily be expanded by its developers to includ additional software packages and/or heuristics. The advice provided by NETSSA is supported with full explanation and reasoning. The user can accept it in whole or in part. NETSSA allows the user to change the relative weights placed on the different aspects and options: assign new we! hts, and declare specific requirements as bemg absolutely cntJcal to the user. These flexibilities enable the user to use NETSSA interactively until he or she arrives at a recommendation that would optimally satisfy his or her agency's" realistic" needs and constraints.

Almost all transportation studies involve systematic analysis processes that include the forecasting of traffic flow patterns on several elements of transportation systems (J). Microcomputer technology is developing very rapidly and is becoming increasingly available to more transportation planners and engineers. Consequently, several microcomputer software packages have been developed recently to facilitate networkbased traffic forecasting on transportation networks (2). Representative packages include TRANPLAN/NEDS, Micro-TRIPS, EMME/2, TMODEL2, MINUTP, TRANSPRO, MOTORS, JHK SYSTEM II, CARS, etc. Although these packages predict traffic flow patterns on transportation networks, their capabilities and limitations differ in several aspects such as maximum allowable network size (ie, number of zones, nodes, and links), hardware requirements, trip generation capabilities, trip distribution options, modal split approaches, traffic assignment techniques, output reporting options and formats, interactive graphic facilities, prices, maintenance costs, technical support, ease of use, compatability with existing computational facilities,