Optimal allocation of designated bus lanes in multi-modal urban networks

Road space distribution among multiple modes of transport in contemporary urban environments has attracted the interest of several researchers and policy planners. Revealing the relation between road space share and global performance of the network would result in more efficient transport system design. The introduction of dedicated bus lanes in parts of the network has been proposed as a measure to allow high occupancy vehicles to travel through regions with high traffic load without long delays. In this way, the bus-system operates more efficiently and is more competitive to the private car option in terms of travel time. This effect can stimulate a significant mode shift to bus use and alleviate congestion by reducing the number of low occupancy vehicles. In this work we address the problem of optimal allocation of exclusive bus lanes in a given multi-region multi-modal urban network with the aim of minimizing the total passenger hours travelled (PHT). A queueing theory based traffic flow model, known as the Store-and-Forward (SF) model, is utilized to simulate the evolution of congestion inside the network by keeping track of the queues inside all links over time. Our goal is formulate this problem in a Mixed-Integer Linear Programming (MILP) form and attempt to solve it to optimality