Headways on High Speed Lines

Some parts of the European high speed line network are near saturation. ETCS-L2, the so called Level 2 of the European train control system, standard for providing signalling and automatic train protection (ATP) on new high speed lines (HSL), offers a pretty good level of capacity. However, even with the mobile block system provided by ETCS-Level 3, it seems quite impossible for the practical capacity to reach 20 trains per hour per HSL track as soon as maximal speed is at 300 km/h or higher. At very high speed, headway between trains is mainly determined by the braking performance of the trains. The paper presents a new running mode using relative braking distances on one hand, and keeping absolute emergency distances in any case on the other hand. The devised running mode is here described within the classical ETCS_L2 context, where signalling still uses track circuits or axle counters. This secure mode of operation could offer a practical capacity more than 20% higher than the today ETCS_L2 Full Supervision mode.