Travel Demand Management (TDM) case study for social behavioral change towards sustainable urban transportation in Istanbul

In order to realize sustainable cities, it is vital to achieve and maintain social behavioral change for shifting our modes of mobility from inefficient, wasteful and motorized means to cleaner, greener, healthier and more economic means such as walking, cycling and public transportation in addition to smart use of land, intelligent transportation systems, and clean and green vehicles. This study is based on a critical review of literature in order to establish a framework of social behavioral change policies, particularly developed and tested for urban mobility and traffic congestion. First, various mega cities were compared on different sustainability indicators to better understand the case of Istanbul. Then, selected policy potentials, namely Travel Demand Management (TDM), were evaluated for Istanbul following a set of personal interview surveys aiming to reveal travel patterns of residents, their perceptions and attitudes on current transport system performance, and their opinions for possible TDM interventions in the future. We proposed a multiplicative model to process data from these surveys as inputs, which would then be used to determine travel demand. A simulation model was constructed using PTV-VISSIM tool and validated with current traffic congestion metrics obtained from field measurements in a selected district of Istanbul. Based on this validated simulation model, projections of traffic conditions in the future under different TDM scenarios were predicted with the help of determined TDM potentials obtained from the survey results. As a result of this study, it was revealed that the traffic congestion levels in Istanbul tend to become worse year by year under existing conditions, but it was also found that the TDM policies offer significant potential for reducing congestion, hence its consequent hazards, via increased use of sustainable mobility modes without the need for new infrastructure investments.