Exploring Virtual Coupling: operational principles and analysis

Virtual Coupling is a next-generation signalling concept conceived to increase railway capacity by bringing moving-block operations one step further to separating trains by a relative braking distance, like cars on the road. Thanks to a Vehicle-to-Vehicle (V2V) communication layer, trains can move in virtually coupled platoons which can be treated as single convoys at junctions to improve capacity. This concept however introduces the need for additional operational constraints, especially at diverging junctions, which could make capacity gains insufficient to justify investments. The railway industry is hence investigating the benefits that Virtual Coupling can offer with respect to moving-block and fixed-block signalling systems. This paper introduces operational principles and an innovative train-following model capturing operational states and corresponding transitions of Virtual Coupling train operations. A comparative capacity analysis is conducted for a portion of the South West Main Line in the UK. Promising results are obtained, showing that the biggest capacity gains of Virtual Coupling refer to operational scenarios normally found in practice with trains having service stops and using different routes. The analysis of multiple disturbed scenarios reveals that performance improvements of Virtual Coupling over moving-block are instead only marginal on low-speed networks.