Safety Envelope Management Method for Marshaled Trains Based on Time Delay Protection

[Objective] In flexible marshaled trains, the communication delay between the master railcar, subordinate railcar and ZC (zone controller) exhibits asynchrony, leading to potential issues such as overlapping, misalignment, and discontinuity in the safety envelopes of different trains. To enhance the accuracy of ZC in managing the safety envelopes of flexible marshaled trains, it is essential to study the message delay differences among different trains. It is aimed to dynamically manage the safety envelopes of marshaled trains under the premise of delay protection. [Method] A scenario analysis of the positional relationships among marshaled trains is conducted. A typical safety envelope handling solution for marshaled trains is introduced and the improved one is proposed, a comparative analysis between the two solutions is conducted. [Result & Conclusion] ZC and VOBC (vehicle on-board controller) calculate message delays with interactive delay calculation parameters. By comparing the delay status between the master and subordinate railcars, ZC dynamically calculates the safety envelope for marshaled trains. Unlike relying solely on the master railcar for extending the envelope, ZC can use the current position of the subordinate railcar for calculation when the master railcar position is uncertain, avoiding situations where adopting historical information causes delays in updating position reports promptly. The issue of low safety envelope accuracy when master railcar communication quality is poor, thereby enhancing the management precision of ZC controlled trains.