Roslagsbanan: A capacity comparison between the current ATC system and the implementation of a CBTC system

Sammanfattning: Communications-based train control (CBTC) aims to improve headways in the railway systems while maintaining or even improving safety. By means of the CBTC systems, the exact position of a train is known more accurately than the traditional signalling systems. It is a continuous, automatic train control system utilizing high-resolution train location determination, independent from track circuits. The system makes use of the telecommunications between the train and track equipment for the traffic management and infrastructure control. Roslagsbanan is a narrow gauge urban railway system that connects Stockholm with the northern suburbs of the city and despite its age and limited capacity, it is one of the most used railways in Sweden. From the beginning, the entire track consisted of single-tracks where the trains had to wait for each other on special meeting tracks. Αn expansion plan is now underway and the authorities are building approximately 22 km of double-track where the trains will be able to meet. All work along the Roslagsbanan aims to increase capacity, safety and accessibility. With more double-tracks and an updated signal system, the risk of traffic disruptions will be reduced and it is possible to have more frequent traffic in the future. This master’s thesis investigates a CBTC implementation in Roslagsbanan according to the current expansion plan and comparisons are conducted between the current capacity of the ATC system. A simulation model is developed that calculates the train’s safe braking curve and safe braking distance and two case studies are examined. The first one: Calculation of the capacity of the train routes and examination a capacity increase by a minimum 20% during rush hour, taking into consideration the current expansion plan in double-tracks. The second one: Calculation of the capacity of the train routes considering double-tracks the entire route. In this way, differences could be seen between the traffic density with single and double-tracks. Several insights were gained during the realization of this project and as well as timetables have been created to visualize the findings of this thesis. The timetable’s regularity time is decreased to a significant degree and more frequent traffic can be accommodated. Furthermore, the capacity is definitely affected by the track/infrastructure design however, it is questionable whether this increase in capacity outweighs the economic factor of expanding the entire route to double-tracks.