The three stations are north of the Alps in central Switzerland, and, in one sense or another, each of them can be said to be at the centre of the Swiss rail network.

Rail map of central Switzerland. Adapted from the Map of Switzerland at Railways through Europe
Zürich HB (Zurich main station)
In the realm of rail passenger transport, Zurich main station is a main node for international long-distance trains, the biggest node for the network of domestic long-distance trains, and the centre of Switzerland's biggest rapid transit network. All this traffic has to use the 16 stub tracks under the 7½-nave station hall (built in 1933), two stub and four through tracks underground, and four temporary stub tracks which will be replaced by four more, in-construction through tracks underground.

Above: SBB RABDe 500 034 "Gustav Wenk" and (in the shade) a sister, a pair of tilting trains of the Swiss Federal Railways (SBB), stand ready for departure on a domestic ICN service to Lugano in southern Switzerland
Below: Budapest-bound railjet semi-high-speed puss-pull train of the Austrian Federal Railways (ÖBB) with driving trailer "Spirit of Hungary" and ÖBB 1116 207 at the other end on the left and Paris-bound TGV POS unit #4417 high-speed train of the French State Railways (SNCF) on the right share a platform. These two connecting services are the modern replacement for the famed through service of olden times, the Arlberg-Orient-Express

With almost three thousand trains arriving and departing every day, there is truly constant movement on the approaching tracks.

Three arrivals within seconds: on the right edge, the end of a domestic InterRegio (IR) push-pull train from Biel/Bienne; on the left, an ICE1 high-speed train of the German Railways (DB) from Hamburg; and at centre, a Siemens-made SBB class RABe 514 double-deck S-Bahn train on the ramp to the underground through platforms
Following a referendum in 1981, Zurich's commuter rail services were organised into an S-Bahn rapid-transit network. This required several network enhancements, above all the underground platforms and two connected longer tunnels providing for through services. Opened in 1990, and enhanced several times, the system grew into a monster, carrying over 400,000 passengers a day (in a metro region of 1.5 million inhabitants) with an ever increasing number of double-deck trains.

The then brand-new SBB RABe 511 023 double-deck train, the Zurich S-Bahn version of the KISS double-deck train platform of Swiss maker Stadler, in unusual role as IR to Schaffhausen
To increase capacity, a second tunnelled bypass for through connections (grey line curving to the north on the map) with additional platforms under the main station is in construction (for completion this summer). The construction site marred the view on the street-side station front, belonging to the 1871 single-nave terminus building. Since the 1933 reconstruction, the latter is in use as a spacious concourse; last October, a third of it was occupied by a loud beer tent trying to bring Munich's Oktoberfest to Switzerland.

Luzern (Lucerne)
Lucerne's 1896 terminus was one of the most beautiful in the world, also because of its geography: its five naves look south at approaching tracks that turn sharply in front of a hill, making for a special light effect. The concourse part of the 1896 building, however, burnt down in a major fire in 1971, subject of the 16-minute Swiss-German documentary below (move forward to 4:35 for the most spectacular part):
Only the central entrance remained as memento, while the new station front (completed in 1990) is further back. Inside, there is an upper level with a restaurant with 'panoramic view' (I made the photos above the fold and further down from its balcony), I dined at a cheaper restaurant on the underground passage level, though.

A decade or two ago, the advocates of rail privatisation often pointed to Switzerland, where per capita train rides are the highest, service the most reliable, yet a large part of the network was operated by private railways. They forgot to add that almost all of those "private" companies were majority- or fully-owned by local or canton or national governments, and they didn't compete with each other but cooperated to run an integrated system. Still, after half a century with little changes, the last 15 years saw a major consolidation phase: almost all major normal-gauge railways became part of either the Swiss Federal Railways (SBB), or a major semi-private railway in the west majority-owned by the Canton of Bern (BLS), or a similarly semi-private major railway in the north-east (SOB); and the last three of the six main metre-gauge mountain networks got a single operator each (including the one I showed here). Lucerne is the meeting point for all three big standard-gauge operators as well as the Zentralbahn, one of the big metre-gauge operators (which is two-thirds owned by SBB and uses the lower-case acronym zb).

Looking along the westernmost nave. On the left: SOB's VorAlpen-Express train from Romanshorn (on the shore of Lake Constance); on the right: a BLS RegionalExpress (RE) train from Berne; behind both, you can make out SBB double-deck push-pull trains waiting for departure as IR trains to Basle resp. Zurich. All of these services are hourly
The narrow-gauge part is the easternmost nave. Operator zb was born from the 2005 merger of a larger SBB-run railway to Interlaken Ost (at the foot of the Bernese Oberland tourist region) and LSE, a smaller semi-private railway to Engelberg (a resort town), both with rack sections. This resulted in the use of old rolling stock in non-ancestral areas, but there are a lot of newer vehicles. The first of these came with the 2004 establishment of the Lucerne-centred S-Bahn Mittelschweiz network (which is marred by the postponement of a tunnel for through services, but a 2009 referendum approved funds for planning), more came recently.

Above: zb ABeh 160 002, a brand-new unit of a type nicknamed "FINK" (finch), as IR to Interlaken Ost; in front of zb ABe 130 003, of a type nicknamed "SPATZ" (sparrow), which arrived on an S-Bahn service. The contrast showcases the in-house development of Swiss maker Stadler over eight years
Below: zb (ex SBB) HGe 4/4II 101 965 (built in 1990 as a member of a powerful standard type for several Swiss metre-gauge rack railways, see others here) with an express train to Engelberg in front of the building of a vocational school

Arth-Goldau
Arth-Goldau station, situated on the watershed between two large pre-Alpine lakes, is the northern gateway to the Gotthard railway: the lines from Lucerne and Basel resp. from Zurich meet. It is also the endpoint of the SOB mainline, a node of the S-Bahn Mittelschweiz network (which includes a line run by SOB), the endpoint of a rack railway from the Rigi mountain, and there are several sidings for freight trains. Currently, passenger trains from all directions, including ones of different class along the same route, are scheduled to meet at the same time with enough time for transfers.

From left to right: an SOB VorAlpen-Express from Romanshorn to Luzern (with SOB [ex BT] Re 456 096 at the end), an SBB IR from Luzern to Lugano (with the advertisement-clad SBB 460 003 in front), an empty track on which a late SBB ETR 470 tilting train will arrive as EC from Zurich to Milan, SBB RABDe 500 043 "Harald Szeemann" as an ICN from Zurich to Lugano, and a brand-new SOB class RABe 526 commuter EMU (a Stadler Flirt) as S31 to Biberbrugg
SOB's VorAlpen-Express trains are actually operated in cooperation with SBB, and the south-western end of the route, the tracks from Arth-Goldau to Lucerne belong to SBB. When I wanted to go to Lucerne, I wondered whether my rail employee free ticket for SBB is valid for the trains or not, but couldn't figure out from info material at the station (and there was a line at the help desk). What's more, the VorAlpen-Express that arrived had an SBB loco, and the car next to me lacked a SOB designation, so I said what the hell and boarded it. When the conductor came, he told my ticket is not valid in spite of the joint operation and the SBB tracks, but he shut an eye for a colleague and was very helpful to explain the situation. Which was mostly what I already knew (that SOB is not the SBB and I could have requested a different rail employee free ticket for it), but I didn't interrupt him :-) Inside, the SOB cars were especially luxurious: lots of leg freedom and desks for all seats even on 2nd class.

The hourly IR service along the Gotthard railway is actually the combination of two-hourly services from/to Lucerne and Zurich. On the first day of my first trip (which was a day of heat records), the train I took from Salzburg to Zurich was an hour late (most likely due to an accident in Hungary), so I had to board an ICN and change trains in Arth-Goldau.

But what I call attention to on the above photo is the smoking girl: while Swiss trains are non-smoker-only, there are no nationwide restrictions on stations. German and Austrian stations had those for years, and a total ban for all passenger areas of all public transport was introduced in Hungary two years ago. While these bans are violated regularly by defiant morons in all three countries, they still make a big difference, which got me de-acclimated, thus when I set foot in Zurich HB for the first time, the all-permeating stench produced by dozens of smokers spread out in the big hall hit me like a wall. As for restaurants, comprehensive smoking bans are limited to specific cantons, and the one Arth-Goldau is in (Schwyz) lacked one, so I was again unpleasantly surprised upon entering a kebab restaurant.
The latter brings me to another observation: if measured by simple spending items like a kebab or a cola or a bus ticket and using official exchange rates, Austria's price level is almost twice that of Hungary, and the places I have been to in Switzerland are again almost two times that.
I close with two photos made in the dusk. As a general observation, locals seem accustomed to, and mindful of, train photographers: even dozens of metres away, they walked out of the picture without asking.

Above: My IR from Zurich on the first day of the autumn trip stopped at Arth-Goldau, with the then brand-new SOB RABe 526 052 as S31 to Bieberbrugg at the other platform
Below: a VorAlpen-Express from Lucerne to Romanshorn with SOB Re 446 015. This is the former SBB Re 4/4IV 10101, the first of four prototypes of a famed class never built in series, because their then new technology (DC motors fed without switching by thyristors) was eclipsed by the now universal technology of asynchronous AC motors and AC–DC–variable-AC converters

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In the final diary to utilise photos of my two holidays last year across Switzerland and Austria, I shall return to the northern section of the Gotthard railway (sometime in the coming weeks).
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