Rail transit is one of the most important public transportation types, especially in big and crowded cities. Therefore, getting a high customer satisfaction level is an essential task for municipalities and governments. For this purpose, a survey is conducted to question the attributes related to rail transit network (metros, trams, light rail and funicular) in Istanbul. In this study, we present a novel framework which integrates statistical analysis, SERVQUAL, interval type-2 fuzzy sets and VIKOR to evaluate customer satisfaction level for the rail transit network of Istanbul. Level of crowdedness and density in the train, air-conditioning system of trains' interior, noise level and vibration during the journey, and phone services are determined as the attributes need improvements. On the other hand, different improvement strategies are suggested for the rail transit network. The proposed approach provides directions for the future investments and can be generalized and applied to complex decision making problems encounter inexact, indefinite and subjective data or uncertain information. (C) 2014 Elsevier Ltd. All rights reserved.