Conflict detection and resolution for distance-to-go railway signalling

Abstract

Conflict detection and resolution models typically consider train separation distances based on a number of blocks corresponding to conventional fixed-block signalling systems. However, modern distance-to-go railway signalling systems, such as the European Train Control System (ETCS), use braking curve supervision, resulting in train- and speed-dependent train separation distances. This paper proposes a modelling approach that incorporates train- and speed-dependent brake indication points and the resulting blocking times, enhancing conflict detection and resolution models for distance-to-go signalling. By integrating these enhancements into the state-of-the-art RECIFE-MILP model, a mixed integer linear programming formulation explicitly representing fixed-block distance-to-go signalling is obtained. The enhanced model is evaluated considering the state-of-practice fixed-block distance-to-go signalling system ETCS Level 2, and is compared with the original model for conventional fixed-block signalling in two real-world case studies. Results show that the shorter train separation under distance-to-go signalling leads to different rescheduling decisions, including a significant number of reroutings and some reorderings. With that, reductions in total train delay are achieved for 98% and 55% of the respective case study instances. While the mean reductions are below 1%, reductions of up to 7% are observed. These findings illustrate the operational relevance of incorporating distance-to-go principles into conflict detection and resolution modelling.