If the EC Munich-Zurich arrives with more than 2 minutes delay at the Swiss border station of St. Margreten it is getting "isolated" and has to follow the S-Bahn with +30' as an end result, that's the other extrem...
Another thing the Swiss control staff/signallers do really well, which the Germans as far as I know do not (no idea about the UK) is having specific playbooks for different situations already pre-planned, so if some kind of disruption occurs, there is already a ready-made plan in which all the conflicts are taken into account and minimises overall disruption - including which connections to hold and which not to.
For example, the plan for the Munich-Zurich EC was updated based on past experience relatively recently (as posted on the
swiss rail forum), and shows which path the train should take, based on its delay upon entering the Swiss railway network in St. Margrethen, and its resulting arrival delay in Zurich.
St. Margrethen | Path | Zürich HB |
up to +5', max +6' | Scheduled path | on time, Löwenstrasse*, Reverse in Wollishofen |
+5' to +9', max +10' | from St. Margrethen behind IR13, in St. Gallen overtake IR13, in Eschlikon overtake S35, from Grüze behind S11, from Winterthur behind S8 (applied since 23. June 2023, previously behind IR13 until Zurich HB resulting in +25') | about +10',
Löwenstrasse*,
Reverse in Wollishofen |
9' to 12', max +13' | from St. Margrethen behind IR13 | about +25',
Löwenstrasse*,
Reverse in Wiedikon |
12' until approx 30' | from St. Margrethen behind S2, in St. Gallen if possible same-platform connection with IC5, from St. Gallen behind IC5 | about +35', surface platforms, reverse there |
from +30' to about +42' | from St. Margrethen behind S5, from St. Gallen behind IC1 | about +55', Löwenstrasse*, stepping back** to return working |
from +42' | from St. Margrethen behind S4, from St. Gallen run on scheduled path an hour later, potentially behind peak-only IC5, and reach Zürich about +65' or terminate short in Winterthur | about +60', Löwenstrasse*, stepping back** to return working |
*
Löwenstrasse refers to the through-running underground platforms 31-34 in Zürich HB. The EC is scheduled to start/terminate in these platforms in order to provide a quick cross-platform connection to the IC1 to/from Bern and Geneva. However, it cannot wait for its return working there without blocking through-running S-Bahn services in between, so runs out of service to some sidings in Zürich Wollishofen (on the left bank of Lake Zurich) to wait there. Zurich Wiedikon is two stops short of Wollishofen. The German word for this maneuver is called a "Fluchtfahrt" which literally translates as an "escape trip"
** Yes, SBB use stepping back on mainline rail services, including the flagship IC1 line in Geneva Airport. There would be no way of reversing a 400m (or in the case of the EC 200m) train fast enough otherwise, especially for through services via single-ended platforms.
Having plans like that for every service and possible route blockage makes the control staff's actions much more predictable and less likely to cause unnecessary conflicts with other services. It also allows much cleverer solutions to be used.
For example in the case for 12-30 minutes delay, the EC takes an entirely different route between Zurich Oerlikon and Zurich HB via Zurich Wipkingen in order to end up in the surface platforms (which have no rail connection to Löwenstrasse from the Oerlikon side). The same-platform connection in St. Gallen allows the onward connections in Zurich from the pulse 30 minutes later than scheduled to still be made, despite the EC being 35 mins late in the end, reducing the delay for those passengers from 60 minutes to 30.
Naturally they can't cover absolutely every scenario, but they make making quick decisions much easier and appear to lead to better results. Given how often the EC reaches St. Margrethen late (more often than not), this is probably one of the few plans in which every scenario has been applied in practice more than once...