ERTMS

Hybrid ERTMS/ETCS Level 3 Concept

The ERTMS is ... . Its description is available in the paper. The file is available here (theme here). An Alloy version is available here (theme here).

Operational Scenarios

![](images/train_disconnected.png)	![](images/train_connected.png)	![](images/train_front.png)	![](images/train_rear.png)
Disconnected train	Connected train not reporting	Connected train not reporting rear info	Connected train fully reporting
![](images/train_mute.png)	![](images/train_disintegrated.png)	![](images/train_front_pos.png)	![](images/train_rear_pos.png)
Train with expired mute timer	Train with expired integrity timer	Actual train front position	Actual train rear position
![](images/vss_free.png)	![](images/vss_occupied.png)	![](images/vss_ambiguous.png)	![](images/vss_unknown.png)
Free VSS	Occupied VSS	Ambiguous VSS	Unknown VSS
![](images/vss_disconnect_timer.png)	![](images/vss_integrity_timer.png)	![](images/train_ma.png)	![](images/vss_jumping.png)
VSS with expired disconnected propagation timer	VSS with expired integrity loss propagation timer	MA assigned to a train	Jumping train info
![](images/ttd_free.png)	![](images/ttd_occupied.png)	![](images/ttd_shadow_a_timer.png)	![](images/ttd_shadow_b_timer.png)
Free TTD	Occupied TTD	TTD with expired shadow timer A	TTD with expired shadow timer B
![](images/ttd_ghost_timer.png)	![](images/ttd_vss.png)
TTD with expired ghost propagation timer	VSSs comprising a TTD