Mastodawn

Having discovered SNCF's newest Alstom built Avelia Horizon TGV-M trains do not fit Italian tunnels, I set about working out how everything got into such a tangle

Turns out the 1973 oil crisis and a 2009 decision of the UK government are central to it, and you can even go back to 1871 in Japan to explain part of it as well

Take a trip into the history of French high speed rail 👇
https://jonworth.eu/rail-path-dependency-how-the-oil-crisis-and-the-british-government-left-sncf-with-a-problem-in-italian-tunnels/

Rail path dependency: how the oil crisis and the British government left SNCF with a problem in Italian tunnels

When writing my previous post about the loading gauge of SNCF's Alstom built TGV-M Avelia Horizon train being too large for Italian tunnels, I had this nag in the back of my mind: how did they get themselves into this tangle? And it is not the first time I have

Jon Worth

Gerben Vos 5d ago

@jon Minor but confusing typo: "that one was one by Talgo instead." -> Second one should be "won".

Jon Worth 5d ago

@gpvos Oops, thanks, will correct!

The Penguin of Evil 5d ago

@jon The same SNCF who ordered trains too wide for its own platforms 8)

Ela - TechnicalOtter 5d ago

@jon I suspect that the Avelia Horizon will become a nightmare in service and you'll end up with boarding ramps or inacessible trains because that active suspension *will* fail.

I come at this from the perspective of the UK, where we engineered a train that would foul the loading gauge of an adjacient line if it's active tilt system failed.

Jon Worth 5d ago

@technicalotter I think it will be good enough, just, in France. Hell knows what it will be like in BE, NL...

Ela - TechnicalOtter 5d ago

@jon Oh yeah it'll be fine in France. If the active suspension fails, it's still accessible. But if it fails when you roll over the border, you're screwed.

@jon just looked the only single deck trains Alstom recently sold is the avelia liberty. Does SNCF still do intercity trains? 15 yrs ago they existed ( strasbourg southwards towards belfort at least). What about a 280km/h pendolino for intercity services? All the Duplex TGVs likely mean there is quite a gap for this. I know current SNCF wont do it. But there sure is untapped demand. You can even send those trains abroad w/o headaches

Jon Worth 5d ago

@vermeer Stream. It's mentioned. 300km/h post Pendolino

Anders Norén 5d ago

@jon
Speaking of which: I find only one example of a tilting train with a top speed of 250 km/h, although they would make sense at least in Sweden, which is the Cisalpino Due. But Wikipedia mentions that they were too heavy when fitted for 15 kV/16 ⅔ Hz and have to go with reduced speed in Switzerland. Are tilting trains capable of speeds >200 km/h too heavy with 15 kV transformers? 25 kV/50 Hz equipment is lighter.
@vermeer

Jon Worth 5d ago

@violanders @vermeer no. Swiss ETR610 is 250km/h and tilts and has 15kV

Anders Norén 5d ago

@jon
That's the one. Has it been allowed to go full speed in Switzerland now?
@vermeer

@jon I demand this will be turned into a Wendover video

@jon maybe a Collab with @TechConnectify ?

Jon Worth 5d ago

@photom This is probably more one for The Tim Traveller! @TechConnectify

Tachibana Kanade 5d ago

@jon Looking at https://masto.ai/@bovine3dom/116250312099483651 it seems unlikely that every km of line in a country will have the same loading gauge constraints—do you think it’s possible that they just measured for the lowest common denominator, and if they went and reassessed in more detail, some routes could be cleared to larger loading gauges (even if not full GB, then an intermediary one tall enough for TGV-M)?

Oliver Blanthorn (@[email protected])

Attached: 1 image new map for you all: "how big can trains be?" across europe using declared loading gauges from the ERA RINF. purple = big trains, red = small trains, green = somewhere in between. https://compute.olie.science/expo/?data=loading_gauge/2026-03-18#x=8.0973&y=48.8056&z=5.0605 thanks go to @[email protected] for helping with the data. all mistakes are my own :)

Mastodon

Jon Worth 5d ago

@h0m54r Maybe, but no, this doesn't answer the issue entirely. In the EU Agency for Railways database you can get data per section of track, not an entire route. Why not then show the correct data per section?

Tachibana Kanade 5d ago

@jon At a guess, because they might measure the clearance by running a particularly sized measuring device through? So if they know one section is G1, they run through the entire line at G1 to check it fits, and then the entire line gets classified as such? I’m just speculating though.

Tachibana Kanade 5d ago

@jon (Given how motion sick going backwards on the top deck of a TGV Duplex makes my partner, I really hope they come up with a better solution—seats that can rotate to always face forward, a reservation system for Interrail that lets you select the bottom deck, anything!)

Jon Worth 5d ago

@h0m54r Rotating seats: they tried it, they broke, they abandoned it. Better booking system: doubt it. SNCF always knows better what you need than you do, remember! So I have no good news for your partner, sorry.