Congested multimodal transit network design

The planning of transit services is vital to transit-oriented metropolises. It is a complex, multi-objective decision process, especially for services operated by the private sector. Traveler’s desire for direct, affordable, and quality services often conflicts with the profit-making objective of private operators. In a multi-modal network, partly collaborative and partly competitive interactions among transit modes further complicate the problem. To simplify the planning problem, existing studies generally consider transit network design from the perspective of a single mode while neglecting the modal interactions. The lack of a comprehensive approach across transit modes may result in an unbalanced supply of transit services, weakening the financial viability of the services and, more importantly, adding unnecessarily to congestion, especially in already congested districts. This study explicitly considers these interactions in a multi-modal network framework. We develop a systematic phase-wise methodology for multi-modal network design, considering both the effect of congestion and integration of modal transfers. Inter-route and inter-modal transfers are modeled through the State Augmented Multi-modal (SAM) network approach developed in earlier studies. An illustrative example is included to demonstrate the design procedure and its salient features.