Simulating and Evaluating the Lötschberg Train Traffic System

The Lötschberg Base Tunnel is a 34.6 km long railway tunnel, consisting of a 19 km single track section. This poses particular challenges for the tunnel operation to minimize track occupation conflicts. For this reason, a train traffic control system is in operation that forecasts train movements, calculates optimal speed trajectories and sends corresponding advisory speeds to the train drivers, who can in turn adjust their speed.
The aim of this thesis is to analyze the added benefit of the existing control system compared to an operation without speed recommendations, and investigate on further possible improvements.
We have developed software to simulate conflict situations with and without an advisory speed system. The results are shown in combined speed-distance, force-distance and time-distance plots. This visualization enables an in-depth interpretation of the conflict situation and driver behavior. To evaluate the overall impact, we calculated four main railway line capacity indicators („number of trains”, „average speed”, „heterogeneity” and „stability”) using a quantified model. They can be compared in a spider chart in our web-based analysis tool.
Simulation results show, that in conflict cases, approximately 25% of the trains are able to leave the single track section at least 15 seconds earlier thanks to the current advisory speed system. Additionally, we estimate that at least 12.5% of energy is saved.
Our evaluations also show that a detailed vehicle dynamics model is very beneficial for the crossing conflict optimization algorithm. We therefore pro- pose an enhanced algorithm, which consistently respects engines’ limitations to improve the resulting speed trajectories towards capacity gains. When such a model is used, we anticipate that in around 65% of the conflict cases, the affected train can clear the single track section at least 15 seconds earlier.