Pendolino's are still used on the West Coast Mainline connecting London, Birmingham, Manchester, Liverpool and Glasgow and I don't really have a problem with them. They're not going away any time soon, until we have HS2 (brand new route and alignment without the curves that need tilting for 125mph running).
Interestingly, they are increasing the speed on some of the northern bits of WCML through changing the bank of the track more. My understanding is that if the bank was too steep, slower running freight trains had issues with it even if faster running passenger trains were fine. With a general increase in the speed of freight trains, the speed differential is less so a higher bank can be tolerated, and I think there are sections of WCML where non-tilting trains can hit close to the speeds of the Pendolinos.
I'm not sure if I'd call Pendolino a dead end? From Wikipedia: "Pendolino is an Italian family of tilting trains used in Italy, Spain, Poland, Portugal, Slovenia, Finland, Russia, the Czech Republic, Slovakia, the UK, Switzerland and China."
In Finland, they seemed to have had a lot of problems with the tilting mechanism in the winter, so new digital hydraulics system was developed for that. Digital hydraulics is a fun concept by the way.
Well, the info says digital tilting hydraulics was tested 2013-2015 without faults and VR decided to install it on all trains. Couldn't find newer info.
I might have been wrong that the tilting mechanism has been completely disabled. A web search turned out only that it has been limited: https://yle.fi/uutiset/3-7047961
And a press release by the railway company from 2011 says that the higher speed enabled by the tilting is no longer reflected in the timetables
https://www.vrgroup.fi/fi/vrgroup/uutishuone/uutiset-ja-tied... I would say that has not changed afterwards.
Either way, travelling slower through the curves has stopped the wobbly feeling for the passengers. So in practice the tilting has been a dead end in real life for the Finnish railways. Even if I did not really follow the argumentation in the article why tilting is a dead end.
> The Pendolino itself is a fine product, with the tilt removed. Alstom uses it as its standard 250 km/h train, at lower cost than 350 km/h trains. It runs in China as CRH5, and Poland bought a non-tilting Pendolino fleet for its high-speed rail service.
I've travelled London-Glasgow quite a few times over the years since the 90's and I've noticed that the timetable has got gradually slower and slower recently and now it's no faster than the 40 year old trains they replaced in the late 90's. The fastest time went from 5:00 down to about 4:20 when the pendolions were first allowed to go at full speed. But now there seem to be only about 2-3 trains a day that do it in less than 5hrs. TBH, if it's going to take 5hrs+ they might as well have stuck with the old style trains as they had more comfortable seats with better legroom.
Do you not find the WCML a bit of a rollercoaster ride in places? There’s definitely a few points where you’re being buffeted and tilted all over the place unpleasantly.
I can’t believe they’re going to make parts faster? Tea will be flying everywhere.
few bits in the Thames Valley if I'm walking back from the buffet car or whatever, but the bits they're making faster are the bits through the Lakes and Borders and whenever I've been on the Transpennine 110mph trains I can't say I've found it particularly bad compared to the 100mph ones it replaced. (Not been to Scotland on one of their new 125mph trains yet and I don't know if they'll be authorised to run at full speed)
Isn't it inevitable that sooner or later a train will be on that section of track moving slowly? So any train that can go on that track has to be capable of staying on track even if they are stopped or barely moving.
Sticking with Alon Levy's usual act of just dunking on American rail designers, I always laugh whenever I pass over this stretch of the SFMTA Muni light rail line between Townsend and 2nd, where the track is banked as if the streetcar was going to go around it at 80 MPH, even though the track is posted as 5 MPH max for LRVs and Muni's average speed is, last I read, 1.7 MPH, or half a human walking pace. Riding the streetcar over this track, or coming to a stop there which is very common, you see all the passengers leaning to the outside to counteract the ridiculous bank angle of the tracks.
You can’t talk about tilting trains with mentioning the ill-fated British Rail Advanced Passenger Train that started in the 1960’s. The article gives it a short mention.
“Iwnicki thinks the biggest problem with the APT, devised in an atmosphere of "blue-skies thinking", was that it included too many innovations at one time. The casing, bogies, tilting and other features were all new - setting itself an impossibly high benchmark for success. But these have since become commonplace around the world, he adds.”
Well how are you making them, how many are you making and how much do alternatives cost?
Economics vary wildly over time pending circumstances, but are irrelevant to the question of whether something is a technological dead end. To be a technological dead end there must be an alternative technology that accomplishes the same feat in a fundamentally superior way, such that regardless of the economic situation or future development it always makes sense to go with that alternative outside of niche applications.
No, the problem here is there are only a few trains in the world that need this technology. Thus there are very few to amortize the costs of more R&D over. Tilting as a whole is a dead end: passengers get sick where it is used. The replacement is don't tilt your trains on corners at all - thought there are other technologies that are already more reliable as well if you must.
So this tilting is entirely for passenger comfort?
When presented with "you can get there in 1 hour, but you can't put coffee on the table" or "it'll take 2 hours", do passengers really choose the latter?
A coffee cup is at risk of sliding off a table around 4.5 m s^-2, so much higher than discussed in this article. And coffee would definitely slide off a flat surface in most journeys by car - that's why cars have cup holders.
The tilting causes discomfort. From the article: "In fact the Pendolino had to limit the tilt just to make sure passengers would feel some lateral acceleration, because it was capable of reducing the carbody centrifugal force to zero and this led to motion sickness as passengers saw the horizon rise and fall without any centrifugal force giving motion cues."
True. I regulary used Finnish Pendolinos over 10 years ago and it was a pretty wobbly experience. Nowadays they run with tilting disabled and I had nearly forgotten about it.
Until I travelled on a Swedish X2000 many years later and immediately felt it again. Maybe a bit less wobbly, but pulling you "into the wrong direction" in a more determined way. Not really pleasant and I can easily believe people getting "sea-sick" especially when working on a laptop.
However, without tilting and the same speed the sensation might be worse. I guess we don't know, because without tilting they reduce the speed in curves.
I have the opposite experience (very low "passenger comfort") in tilting trains, and I always thought that this is what actually killed them:
I'm slightly suspectible to motion sickness (e.g. "normal" trains are fine, but sitting in the back seat of a car or in a bus can be a bit of a problem, especially when trying to read something).
When I was on a tilting train once (maybe about 10 years ago? AFAIK they are no longer in use) the motion sickness kicked in pretty hard.
PS: Interestingly, a tilted track (which seems to be quite usual now on newly built high speed tracks) doesn't affect me at all. I guess it was the general "wobbliness" of the tilt train.
There is no difference between tilted track and tilted train from what you can perceive from the passenger compartment, provided the tilt is done correctly.
I suspect tilt angle was perhaps rounded/approximated/delayed, which would feel the same as if someone had laid the track rather haphazardly on a bog...
AFAIU, the passenger compartment will indeed have identical angle and acceleration in both cases, as there is no other way to cancel lateral force.
What is likely different is the stability of tilted tracks (reasonably easy to make nice continuous tilts and turns) and tilted train's uncannily small lateral force, while still having time and angle discrepancies and inferior smoothness causing very noticeable over and undershoots.
There are two main types of tilt: active and passive. Active tilt uses a computer, armed with track geometry knowledge, to control the tilt. Passive tilt is just the centrifugal force automatically tilting the train.
The first one is very comfortable. The second is probably what you rode -- it's pretty bad.
Speed limits are set for passenger comfort rather than the fastest speed a train could safely travel.
The equation for the speed limit for a curve is a combination of the radius of the curve, the relative elevation of the outside rail (superelevation) and the allowable “unbalanced superelevation” of the train itself, how much lateral force the train is permitted to have going around the curve. You could design a railroad where the outside rail was raised enough to not feel any lateral forces effects of curves, but speeds will be much lower. Typical trains have 3 or 4 inches of unbalanced superelevation, but a tilting train can drive this number much higher to 7 to 9 inches. This allows faster speeds and maintains passenger comfort.
3 or 4 inches seems a tad on the low side, but then again I remember somebody giving an example of a US tilting train being barely faster than a conventional European train on a similar curve due to more conservative standards prevailing across the pond.
In Germany, up to ~5" (130 mm) are permissible on the main line network. In theory and exceptionally, even values up to 6" (150 mm) are possible, although haven't really been used in practice so far as far as I know. The maximum speed for trams/streetcars/light rail is often based on a maximum deficiency of 150 mm, too.
Tilting trains in Germany can use up to ~12" (300 mm) of cant deficiency, but then again in Germany they really seem a dead end so far.
Here in Sweden, the train company SJ had tilting trains for the 2000 model and abandoned the concept for the 3000 model, because passengers complained of discomfort, or so SJ said. A small speed boost is not worth tilting the train.
As a counter point, I’ve commuted daily with X2000 for a few years (except currently, of course). Much prefer it over 3000. Very occasionaly I can feel a little motion sickness.
Once when the tilting was out of order a guy next to me did solitaire with a deck of cards. And then there was a bend, and all his cards ended up on the floor..
Tilting here means getting the carriage to lean into the turn so it's both more comfortable and faster.
The article is a little confusing because it never actually shows a diagram of a tilted train. That second picture is for the normal case where centrifugal force and normal suspension makes the carriage lean away from the turn, which means the center of gravity and the resultant force move out making the whole thing less stable.
Usually tilting is used to turn a 5 hour journey into 4, or 4 into 3. An extra hour will definitely convince some of your passengers they may be better off taking the hourlong hop in a plane; the entire value proposition of a high speed train is convenience and comfort.
It also doesn't necessarily have to slide off a table. There is an ad for the '70s tilting APT in which the person lauding the train has a cup of tea on the table and it's just sloshing out of the cup, which is at best making a mess and losing drink you paid for, and at worst some inconveniently placed burns on your lap.
The 4.5 m/s^2 is static friction. Trains jostle and wobble in addition to the steady lateral acceleration of cornering, which would help break the static friction.
There would be a force towards the outside of the curve, yes.
But that doesn't mean the train would derail: in the extreme case the flanges on the wheels would prevent it, but what actually happens in normal circumstances is the same thing that keeps trains centered on straights. In a nutshell: since the wheels have a larger diameter on the inside than on the outside, and since the left and right wheels are on the same solid axle and thus rotate at the same speed, any deviation caused negative feedback.
The required superelevation for a given curve to eliminate lateral forces depends on the speed of the train; since not all trains travel at the same speed, and you have to account for slow or even stopped trains, the superelevation is always a compromise.
The diagram shows force vectors, not centre of gravity.
Railcare rolling stock typically has low CG. Bogies, switches, and related equipment are located low in the car and have significant mass. The carriage shell itself is typically far lighter construction (less so in the US, due to higher crush-strength requirements based on the assumption that passenger and freight rail share trackbeds, significant enough that it's limited the maximum speed of US-based rail initiatives even presuming sections of dedicated track so long as any shared rights of way exist).
For a CG diagram, I'd expect the CG to remain well within the wheel gague width, resulting in a stable vehicle.
Interestingly, they are increasing the speed on some of the northern bits of WCML through changing the bank of the track more. My understanding is that if the bank was too steep, slower running freight trains had issues with it even if faster running passenger trains were fine. With a general increase in the speed of freight trains, the speed differential is less so a higher bank can be tolerated, and I think there are sections of WCML where non-tilting trains can hit close to the speeds of the Pendolinos.