Exploring the role of transportation demand management policies’ interactions

The integration of Transportation Demand Management (TDM) policies is a challenging issue in urban policy studies. Interactions between policies that are not addressed broadly in the integration context play a main role in the outcome of TDM policy packages. However, different individual daily trip purposes, city development, variations in land use and different levels of decision making about transportation often lead to the implementation of more than one TDM policy at a time. This study examined the role of TDM policy interactions on the macro and micro levels. On the macro level, this study showed that the introduction of two-way interactions in the model could improve the goodness of fit by 15%. On the micro level, we developed the concept of synergy for all levels of two policies. The results show that generally synergy is a function of policies’ levels, and the integration of increasing parking cost with either cordon pricing or increasing fuel cost has greater synergy at higher levels of the two policies. In contrast, the integration of other two policies (i.e. cordon pricing and increasing fuel cost) had no synergy in the examined ranges.