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Optimization in Railways

Railway systems are large, complex and much interconnected organisms. Because of such complexity, of their huge cost and tremendous impact on society, they need to be carefully planned in every phase - strategic, tactical and operational. However, planning and operating railway transportation systems is extremely hard due to the combinatorial complexity of the underlying discrete optimization problems, the technical intricacies, and the immense size of the problem instances.

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Trains movement on a railway network is regulated by the official timetables.  SINTEF developed an interactive tool, based on mathematical optimization, to define  timetables for passenger and freight trains.

During real-time operations, deviations from the official timetable occur quite often, and this requires fast re-scheduling and re-routing decisions in order to recover the network to its regular status and alleviate delays. Train dispatching is usually carried out by trained personnel. Sintef Optimization developed an automatic train dispatching tool which represents the state-of-the-art in Optimization applied to real-time train traffic management. Each time the status of the network changes, the software computes optimal routes and schedules for the running trains in order to quickly recover from current delays. The solution is then displayed for the dispatchers on a screen as a train graph (standard graphical representation of a timetable).

The dispatching tool developed by SINTEF was first developed for the dispatching central in Stavanger, Norway,  where it was in operation during year 2014. For these developments, SINTEF received the AIRO 2014 Best Application award.  Later, the system was adapted to dispatch trains on the iron-ore line, from Narvik to Kiruna, in the northern part of Norway and Sweden. An upgraded version of the tool is currently (2020) tested in some lines in the Oslo area. In the second half od 2021 a new dispatching tooll, devoted to large stations, will be implemented and tested at Oslo central station.

SINTEF Optimization webpages