Those units had some teething troubles though (and in this instance, teething trouble unfortunately means accidents involving people being caught in the doors and dragged along the platform) which eventually led to the whole system having to be taken out of use until additional light barriers had been fitted [1]. Also, the system does have its limitation during the peak periods, especially in the central area: As train loadings increase and people start to pile up in the door areas, they start blocking the light barriers, so you either have to wait until everybody's cleared the immediate door areas, which means unacceptably long dwell times, or you have to go back to central door closing with somebody - either the driver or platform staff - having to make sure nobody's getting trapped in the doors.
Also, on some German rail forums, you can hear regular lamentations how dispatching is now taking longer than it used to with the old stock, with the subsequent hit to reliability this has brought along.
Quite recently, there's been an incident at Stuttgart where somebody died after having been caught in the doors and dragged along the platform, it'll be interesting to see how that will play out in the long run.
[1] If I remember correctly, with the original setup, the light barriers were only present at foot height, while with the new setup, they're now covering the full door height. If I've understood it correctly, the very latest rolling stock generation is now also including something similar to the "sensitive edge" on the new LU trains.
Yes, I was referring to the current set up which has a mesh of infra-red beams close to the doors running their full height, but without the "sensitive edge" doors. The original system was replaced after the
Eisenbahnbundesamt, the Federal body which approves trains for service on the German railways, was taken to court by the State Prosecutor (I can't now remember whether it was a
Land prosecutor or the Federal office) for permitting the use of an unsafe system. Apparently the accident statistics were collected on a Länder level and therefore similar accidents were not being recorded centrally so no overall picture emerged - and it was also alleged that the directorate for the S-Bahn in Munich had rigged the figures. The interesting thing is that it was not DBAG that was charged with procuring and using unsafe trains - but the approvals authority, a state body, for allowing their use.
Anyway it all got very unpleasant - but the long and short of it was that the trains were all re-fitted. The
Eisenbahnbundesamt then seemed to get into defensive mode and as a result, at about the same a time as the doors story (around 2008-9), the ET423s had to have the braking system modified so that they could stop on snow and ice. Subsequent approvals for all new stock has got very delayed. As a further consequence, and because of the influence of the Technical Standards for Interoperability, approvals for new stock are having to be made on a European level, with the unstated reason that the
Eisenbahnbundesamt is being taken out of the loop.
The effect in the UK of all this is that the IEP trains (Class 80x) are being approved via the new European system - although they will never turn a wheel anywhere else than the UK. And this system is impressively bureaucratic - think aerospace. In this context I remember a Boeing Aerospace engineer telling me many years ago when the company I worked for in Germany was shipping components for the E3 AWACS aircraft 'Robert, remember - for every pound of airplane, there are 7 pounds of paper...' Nowadays they are computer files - but the point remains!
One other point concerning the loading dwell times. I agree - this can be an issue during the peaks, but mostly the system works. A similar procedure is also used in tram networks - the doors only close when the top step is free which can cause slight hold-ups in Hannover when many foreign visitors are leaving one of the big exhibitions such as CeBit.
One design feature of the busiest S-Bahn stations in Munich (Hauptbahnhof, Stachus and Marienplatz) is that they have a disembarkation platform so the disembarking passengers do not clash with those trying to get on the trains. This really helps reduce congestion and dwell times although on a recent trip I did notice platform staff in the peak period asking people through the public address system to stand clear of the doors. As far as I could see these staff were only present on the stations between München Ost and the Hauptbahnhof, a total of 6 stations. The staff took no part in the actual train departure but acted more as human hustle buzzers!