The design of a flexible bus line plan

A conventional bus service has a line plan that consists of a set of lines with fixed routes designed to operate under normal conditions. Thus, the performance of the service depends on how stable those conditions are. This paper extends the traditional concept of a line plan to provide a high-quality service, even in case of announced events. We introduce the concept of a Flexible Line Plan where some of the usual lines are replaced with alternative lines that improve the service when the conditions change. Adaptations should only be made to a subset of the lines, ensuring that the changes minimize the inconvenience for the regular passengers and, at the same time, improve the total travel time. In this study, we present a heuristic called Alternative Line Heuristic (ALH), based on Genetic Algorithms, which automatically designs these alternative lines in a three-step process. The results of this approach are tested on both benchmark and real-sized networks and clearly show how our approach contributes to improving the bus service performance.