Description and control of railway traffic flow under a moving block system

Abstract

A moving block system (MBS) will contribute meaningfully to the railway. The advanced system can allow trains to operate closely as a platoon and significantly reduce train headway. Any minor speed disturbance of a train may lead to a chain of changes in operating status for some following trains in a platoon. However, any minor speed disturbance of a train may lead to a domino effect of changes in operating status for subsequent trains. This highlights the need for a thorough understanding of rail traffic flow behaviors under the MBS. Unfortunately, few studies have focused on this area. This study develops a micro-simulation model to describe train movements under MBS, and study in detail two typical railway operation scenarios: steep descending grade and arrival. On this basis, congestion phenomenon and bottleneck effect were explained in combination with the macroscopic rail fundamental diagram (RFD).Moreover, the strong controllability of trains and the predictability of shockwaves make it achievable and promising to control the rail traffic flow under the MBS. This study illustrates rail variable speed limit (RVSL) control in the RFD, and it dynamically provides trains with advisory speed limits to resolve delays and maintain a higher flow at bottlenecks. Two congestion scenarios are considered to evaluate its effectiveness, including the temporary excessive demand upstream of a descending grade and the arrival delay. The results demonstrate that the proper imposition of RVSL control reduces the number of affected trains, delay time, and energy consumption in both scenarios.