External authors:

• Natividad Gonzalez-Blanco ( IMUS , Univ Seville )
• Antonio J. Lozano ( Universidad de Huelva )
• Juan A. Mesa ( IMUS , Univ Seville )

Abstract:

The increase in congestion in surface traffic, airborne pollution, and other environmental issues has motivated transit authorities to promote public transit worldwide. In large cities and metropolitan areas, adding new rapid transit lines attracts more commuters to the public system, as they often reduce travel time compared to the private mode (car) that faces high congestion. In addition, the travel time has less variability with respect to preset schedules, and rapid lines are more efficient than slow modes operated by buses. When a new rapid transit line is constructed, it partially replaces the traffic of existing slow transit lines. As a consequence, some of the slow-mode lines must be either canceled or their routes modified to work properly with the new rapid transit line. This process is usually carried out sequentially, thus leading to suboptimal solutions. In this paper, we consider an integrated model for simultaneously designing rapid and redesigning slow networks. The model's main aim is social: to maximize the demand covered (or captured) by both public modes, through offering a shorter commuting time. In addition, we also take care of the costs, keeping them within limits. We present a mathematical programming formulation that is solved by using a specially improved Benders decomposition. For this purpose, we include a partial decomposition to speed up the computation. The computational experiments are done on a case study based on real data obtained from a survey of mobility among transportation zones in the city of Seville. In terms of performance, for small instances, the Branch and Benders Cut (B&BC) yields solution networks that cover at least 5.2% more demand than other methods in the literature, within a time limit of 4 h. The advantage is even higher for the larger instances, for which B&BC found solutions that the other methods did not find.