Thread by @dominicstucki

This Easter Monday, my local railway bids farewell to its 1992 stock, the class Be 520. This means: Railway portrait time!

Today: Zürich's steepest, quirkiest and loveliest S-Bahn. The #SZU S10 "#Uetlibergbahn", my #MountainMetro. Welcome to my neighborhood!

The S10 connects mount Uetliberg, Zürich's landmark mountain, the Friesenberg residential area and the important work area of Binz with Zürich's main station "Zürich HB" in the city centre.

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The 9.1 km long line is a standard gauge railway, electrified with 1200 V DC and with gradients up to 79 per mil. The line opened in 1875 and is today operated by Sihltal-Zürich-Uetliberg railway #SZU.
Diagram: SZU.

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The line is part of the @zvv's S-Bahn Zürich as line S10. The two #SZU S-Bahn lines S4 and S10 run on their own infrastructure and terminate at Zürich HB instead of using one of the SBB trunk lines through the city. S4 & S10 share tracks between HB and Giesshübel.
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Our journey starts at Zürich HB, where #SZU has its own underground station. Before 1990, the lines ended at Zürich Selnau, roughly 1 km south of Zürich HB.

The underground station at HB was built for the never completed Zürich metro and repurposed for SZU. #MountainMetro

The line leaves Zürich HB in a tunnel under river Sihl. This is the "metro" part of the line, built in 1990. The extension to Zürich HB resulted in an important rise of passenger numbers, making the formerly rather rural lines a "true" S-Bahn.

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1st stop: Zürich Selnau, a bit to the north of the original overground terminus, partly located under the river. Northern entrance looks like a ship. At high water, river Sihl flows around it on both sides.
Maybe interesting for metro station expert @ChittiMarco?
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Selnau station is located quite close to the tram hub of Stauffacher. But as it's a few hundred metres to walk, it often gets forgotten by people. The station features two tracks and is served by both lines, S4 and S10.
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After Selnau, the line climbs to the surface on a 50 per mil ramp. The steep gradient was necessary to reach the height of the road bridge. The tunnel entrance is integrated into the house which was built where the former Selnau terminus once was.
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For the next kilometer, the line runs alongside river Sihl and the former Hürlimann brewery site. The mighty plane tree row along the river is 100 years old and an important recreation area for the inner city.
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South of the Hürlimann site, the line crosses river Sihl and the highway. The huge highway bridge all over river Sihl is one of the biggest urban planning fails in Zürich. Sadly, there is still no project to undo this urban development nightmare.
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West of river Sihl, we reach Giesshübel station. This is where the lines to Uetliberg and Langnau split and where the #SZU depot is located. The station is served only by S4 "Sihltalbahn", as there's no platform at the Uetliberg track.
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This is a good place to explain, what is happening here in the next months. One of #SZU's biggest capacity problems is that the double track line between Zürich HB and Giesshübel is not a real double track section. Problem: S4 runs with AC, S10 with DC!
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In order not to mix AC and DC overhead lines, S10 has an off-centred catenary and off-centre mounted pantographs on the vehicles. This way, AC and DC catenaries can be mounted parallel, as long as they don't cross. Meaning: Only one track can have both, AC and DC.
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The sketch shows the installations.
This system severly limits capacity, as the tracks can't be used for both lines. Only one line can use both tracks, otherwise the catenarys would cross. Maximum possible frequence with this system is every 10 Mins on each line.
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This is not enough, as growing passenger number require a train every 7.5 Mins. #SZU is carring out an investment programme in order to make this possible. Part of it: Converting the Uetlibergbahn to AC for flexible track use.

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The 2013 stock Be 556 is a multi-system unit equipped for AC and DC with a sliding pantograph. The 1992 stock class Be 520 however is DC only and can't run anymore, when the power will be switched this summer. They'll be replaced by an updated version of Be 556.
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After the line branched of at Giesshübel, it passes between two buildings – one of which is my favourite local bakery – to reach Binz station. It serves an important work area in a former clay pit.
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The line starts to climb with 30 per mill. Borrweg passing loop marks the border between the work area of Binz and the green residential area of Friesenberg with a lot of familiy friendly cooperative housing. The suburban part of the line starts here.
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Friesenberg at the upper end of the passing loop is my favourite station. With it's little shop, the small creek and the low and narrow platform, it is very un-swiss. 😉
Behind the high hedge is a jewish cemetery.
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Friesenberg is also the place, where trolley bus line 32 crosses the railway à niveau. No problem with a DC catenary, but with the transition to AC, they're gonna build a complex construction for it. Wondering why the bus can't use the batteries for this section...
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It's only 150m along a little creek between the platform ends of Friesenberg and Schweighof – maybe the shortest distance between two standard gauge stops in 🇨🇭?
Schweighof is a modern stop with high platforms.
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The houses get bigger as apartment buildings replace row houses when we approach Triemli.
This is the city hospital's station and got modernised a few years ago. The limited services terminate here.
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At Triemli, we also reached the city's outskirts. The landscape changes from city to forest here.
Line gradients are up to 50 per mill and get even steeper behind Triemli. This is where the mountainous part of the line begins.
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Through the forest, the line climbs with up to 57 per mill. You can enjoy the view over the city through the trees.

Hidden in the forest, we find Berghof passing loop. Trains cross here Mon to Fri (30 mins takt) but not on weekends (20 mins takt).
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Still in the forest, the line describes a wide curve towards Uitikon. We are now on the other side of the Uetliberg chain.
As a change, here for once a double class Be 566 EMU.
The level crossing in the background got barriers since I took this picture last spring.
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Uitikon Waldegg station is situated above the village at the forest's edge.
Since a few weeks, the station even got its own coffee shop! ☕
A fantastic thing, as quite a lot of my Uetliberg walks end here. 😊
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After Uitikon (pronounced as «Üdike» btw.), gradients get serious. With up to 66 per mill, there are special brake requirements for vehicles running further than Uitikon.
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Ringlikon. Situated in a clearing, this is the last passing loop of the line and the only one which is also a commercial stop. It's normally quiet here, but it can get busy on weekends, as there's a big forest playground nearby.
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Before we'll cover the last part, let's have a look at the rolling stock. Star of the day are of course the eight class Be 520 railcars (full name Be 556 521-528 Be 4/4). Built in 1992, they measure 22m and seat 63 passengers.
de.wikipedia.org/wiki/SZU_Be_4%…
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With 844 kW, they're extremely well motorised and accelerate very fast. The intended driving trailers were never bought. Instead, Stadler delivered four low floor intermediate cars «B 220» in 2003. SZU formed three 4-car consists with 1 or 2 intermediate cars.
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I exceptionally like the «metro style» exterior and interior design. They feature a big multifunctional compartment and wide doors. Note the moquette, the studded flooring and the fabric covered walls! All 90ies retro style now.
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The new kids on the block are the Stadler class Be 522 multi-system EMU (called them 556 before by mistake, sorry!): 50m, 1400 kW, 123 seats.
Six of these 3-car units have been built 2013/2014, another five are in the making or already delivered.
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While I like them as passenger (standard modern EMU, quite enjoyable to ride with, except for occasional motor drone), I think they're extraordinarily ugly from the outside. Out of all questionable designs Stadler ever built, this is imho one of the worst.
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Also I'm not happy with SZU's decision to ditch the traditional orange for a uniform red. Yes, they could run on the traditionally "red" Sihltalbahn, but they make probably 95% of their km on the Uetliberg line. I'd very much preferred the original design proposal.
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That said, let's continue uphill. With 70 per mill, the line leaves Ringlikon and describes wide curves to gain height. Some photographers say, that this is the only spot to make decent pictures of the line. I hope, this thread proves otherwise – at least a bit.
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But yes, it is beautiful here!
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Back in the forest.
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Then, we approach the terminus. The 186m high TV tower comes into view.
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79 per mill!
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Uetliberg Kulm, 813m. Terminus with a view.
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There is a restaurant here, where you can sit on the platform and drink coffee. Of course, it's recommended to take the footpath to Uetliberg peak with a wonderful view. Or even further to Felsenegg (cable car & train back to Zürich) or Albis pass (bus&train back).
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Views from the peak here. 👇 But sorry, no trains that early. 😁🌄
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And now, it's time to face the inevitable. It's 19:00. The probably last ever passenger train worked by class Be 520 arrives at Uetliberg.
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Last photos. There are around 20 fans here to say goodbye and I saw many more during the day – including children happy to see «an orange one». This is also thanks to #SZU's open communication towards us fans. They don't have twitter, but anyway: Thank you, SZU! 😊
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Making of #MountainMetro.

#SayNoToDrones 😁

In the last Be 520 train down to the city. At Ringlikon, the driver makes a short announcement that this is the Be 520's last ride down from Uetliberg with passengers.

Video: The Ringlikon curves seen from the train (without sound, as many people were chatting).
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Farewell, my #MountainMetro! 👋😥

That's it. They're gone. And with the Be 520's 30 years long career, this nearly as long thread comes to an end.
I hope you liked this virtual trip to my neighborhood. Thanks for reading #MountainMetro and have a good start into the new week!
🟥🟧