Complex sentence: The trains can operate at up to on high-speed lines and in the Channel Tunnel; there is an automatic application of the brakes if the speed exceeds, or when the pantograph is in the tunnel setting.
Split into simpler sentences: The trains can operate at up to on high-speed lines and in the Channel Tunnel. Since there is an automatic application of the brakes if the speed exceeds, or when the pantograph is in the tunnel setting.