I checked Wikipedia. Dunkelschaltung allows trains equipped with LZB to pass through the red light signal, automatically extinguishes the red light when passing, and automatically re lights the red light after passing. Excuse me, is it such a short time? Or are there other regulations?
I am not sure what your question exactly is. In general the way you describe it is how it works. Once a LZB equipped train is on a LZB equipped track, its monitored by the LZB center computer, which, in turn, gives orders to the signal box. If the train is now recognized as being the next train to a certain signal, it is switched to dark mode. Once the train has passed, it will switch back on again, as long as there is no further LZB train approaching. The distances LZB looks ahead is different depending on max speeds for the line. For 280kph lines, this is 10km. If for all signals this train is the next train to pass, they will be all in dark mode. The dark mode can be handled differently locally. ASigs and ESigs may also vary, due to local requirements. Also, not all LZB equipped routes use the Dunkelschaltung, however, all true high speed lines do, at least for their route blocks.
Can I presume this is done to increase the signal block length so drivers can remain at higher speed and not have to read signals more than necessary?
Basically, what LZB does is, it allows to keep block distances quite small, but it gives the opportunity to the driver to look ahead through several blocks, so to say. Obviously you will not be able to stop within 1000m at 280kph, hence you need to see what is happening in 7km and further. But you will drive through several blocks.
If you think about what is happening from the drivers perspective and the rules they've been taught, combined with what LZB is trying to achieve: There is a train in the section, it is therefore not possible or appropriate for the signal to show anything other than a red light, because if something is approaching that is not LZB equipped they need to be stopped to remain safe service. If you ARE using LZB however, you have an entirely separate system telling you what to do in the cab, but as a driver, you're trained to stop at reds. Therefore - if you want an LZB train to run into an occupied section, they essentially need another aspect for the LZB equipped driver to not be given bad information, and in this case they have chosen that to be simply turning the signal off. If you were not LZB powered and somehow came up to a dark signal your training would tell you to stop. The end result is a fully safe system which allows LZB trains the ability to run together inside absolute block control without compromising safety of nonLZB trains. Matt.
And this is the reason why on all other TSW routes with LZB there is no dark mode, as the blocks that PZB uses are the same blocks that LZB uses. On these routes the light aspect will always (almost) be the same as the LZB instruction. This is then called the „whole block mode“, vs the „partial block mode“ on Kassel - Würzburg.
In other words: the previous TSW2 routes with LZB in the real world existed before LZB was equipped there. They were upgraded to 200kph but LZB and non-LZB trains run in close proximity to each other. Therefore, the light signals simply are the blocks. On dedicated high speed routes like Kassel-Würzburg light signals are typically only placed in front of potential danger zones (junctions, stations). On Nuremberg-Ingolstadt is a regional train operating from Nuremberg to Allersberg (first station on the high speed line) that does not support LZB. If this train wants to leave Allersberg in the direction of Nuremberg and an ICE just passed, it needs to wait until the ICE has passed the next light signal which could take up to 5 minutes. This obviously brings up the question, how does LZB now recognize this non-LZB train? Along the track are counters for the axles of trains and this information is used find out if a section of track is blocked by a train or not ("Gleisfreimeldeanlage"). All new dedicated high speed routes in Germany (for example Leipzig-Erfurt-Bamberg) are exclusively equipped with ETCS level 2 and in order to enter the route your loco needs to support that. These routes do not support light signal operation.
I guess you are talking about the Ingolstadt Nürnberg Express, which, despite being a regional train, drives 190kph and has LZB equipment on board. When you ask the question how are LZB trains differentiated from PZB trains, I am coming back to the communication between LZB Center computer and signal box computer. The signal box manages the route, LZB only send informations to it and visa versa. The LZB is not interested in PZB trains, only in the information that the route is occupied, in order to send this information to the train. If there is no input from LZB the train is automatically considered PZB only. It’s interesting, all of this is fully automatic. On whole block lines the signaller does not really bother if the train has LZB or not, for him the process of guiding the train stays the same (it’s of course important for him to know, as when LZB on a certain train is inoperative, he needs to consider a max speed of only 160kph). ETCS L2 is basically working the same way as LZB and it’s operational design was heavily influenced by it. However, it only uses balises and is therefore not always aware of the exact position of the train. However, for the purpose of highspeed rail this is sufficient.
True, forgot about S Bahn in Munich. I believe they are also partial blocks?! Not sure, though. Like with everything at DB, things tend to be different everywhere you look.
No, I'm not. There is an Allersberg-Express which, as of 2020, has been renamed to S5: https://en.wikipedia.org/wiki/Allersberg-Express. But I also must correct myself: the train operates with LZB but cannot start with it after reversing in Allersberg.
In this case I hope DB has reserved enough buffer in the timetable I must admit, however, that I don’t know the route very well. Could be that they have taken other measures to compensate for that…
