Malin Forsgren

Maintaining tracks and traffic flow at the same time

In an ideal world, all railway tracks would be available to trains at all times. In reality, track sections need to be closed every now and again for track maintenance and upgrades in order to ensure a satisfactory level of safety and comfort. In this paper, we present a MIP model that optimizes a production plan with regard to both trains and preventive maintenance. The planned maintenance activities may not be canceled, but may be moved in time within pre-defined time windows. Trains may be moved in time, redirected to other parts of the geography, or even canceled. The goal for the optimization is to find the best possible traffic flow given a fixed set of planned maintenance activities. In addition to presenting the model, we discuss the current maintenance planning process in Sweden, and exemplify the usefulness of our model in practice by applying it to two typical scenarios.

Using timetabling optimization prototype tools in new ways to support decision making

The Swedish infrastructure manager Trafikverket is funding research for timetabling optimization tools as part of their overall mission to utilize the existing infrastructure more efficiently. Currently, Trafikverket is modernizing both planning processes and the IT architecture, and will soon be ready to start using optimization tools on a broad scale. Meanwhile, innovative uses of a prototype developed at SICS have shown how a prototype does not necessarily merely serve to pave way for a future, large-scale implementation. This paper shows how computers in railway planning, coupled with OR techniques, relevant data and apt modeling, can help provide a future user with valuable insights even before the full-fledged tool is in place.

Towards shorter lead times in railway timetabling in Sweden

Railway timetabling in Sweden has traditionally been associated with long lead times. In order for the railway sector to be able to compete with other transport modes, the infrastructure manager must become better at meeting the demand for railway services whose need for infrastructure capacity is not well-defined 6-18 months in advance. Research at SICS is changing the Swedish timetabling process so that it will accommodate late capacity requests in a significantly better way than before. This paper describes the principle behind the new method, briefly describes the optimization model that has been developed to support the new process, and presents examples that show how optimization tools can support the new process.