A novel way of building high-speed railways with optimised overhead wire lengths

Sammanfattning: High-speed railways provide fast, comfortable and environmentally friendly transportation for passengers. However, they are fraught with high investment costs that decrease the willingness of governments to construct new lines. This thesis proposes a new way of building high-speed railways to decrease investment costs, where power from overhead wire is, for the majority of a journey, substituted with power from batteries located on the train sets. Not only can the construction and maintenance costs for the overhead wire itself be reduced; as tunnels can be narrowed when no overhead wire is needed, tunnelling costs decrease as well. An algorithm using dynamic programming is devised which calculates the optimal placement of overhead wire given a velocity and altitude profile of a journey, which is then applied on the planned Swedish high-speed line Ostlänken. The cost savings amount in total to approximately 5.689 billion SEK. It is a significant reduction in absolute terms, but is likely even higher, as the cost estimates for electrification are conservative. More studies on this aspect is needed to obtain more exact estimates.