I sometimes entertain myself watching the Thameslink core on the maps at opentraintimes.com. The diagram appears to show block markers in addition to the lineside signals: (almost) all signals have block markers, but there are some block markers without signals (mainly in station areas). I can see why you would want more precise control of the train within a station, but can a movement authority extend to a block marker without signal, or must it be to a lineside signal? The former case would seem to make the route unusable by trains which are not ETCS fitted. Or have I misunderstood things?
The ERTMS used in the core has more sections that the conventional signal sections provided and these were put there to cope with the original proposed train service of 24 tph which cannot be achieved on the conventional signals. The system is set up so that a train running in ERTMS L2 can receive a movement authority to move into a section between two signals when the train in front is passed the next block marker but not passed the next signal, when the system gives this movement authority the signal at which the train is standing will also display a yellow aspect into the forward section (this is contrary to how it has been done on other CBTC systems in other parts of the world and on the underground Central Line where the signal would either have the red aspect extinguish and in some cases also show a blue light).
Thank you for this information! So – no ‘red’ between the yellow and the train in front. This then raises the next question: are trains not fitted for ERTMS L2 prohibited from using this route? (or can it handle these, somehow).
No the system will know if the train is using ERTMS or not and if not then will not clear the signal until the whole signal section is clear. This just as well because only a few drivers are passed to use the ERTMS.