Talk:Acela

The article states that you can now travel Boston-NYC in under four hours. Is this what it's supposed to say? I mean, the distance is about 300 kilometers, if you drive that distance doing 75 km/h (somewhat less than 50 mph) you could go by car in that time.

It's 3 hours 20-25 minutes. Boston to NYC is 346 km, giving a speed of 103 kph (64 mph). That's rarely doable on the Boston-NYC corridor. --SPUI (talk) 23:02, 18 Mar 2005 (UTC)

Tilt

There is an error in the article regarding the decision to use a tilt train for Acela. In fact, there was no rational engineering or technical reason to use a tilt train on the route. It was done for purely propaganda reasons. There are plenty of NON-tilt passenger trains in use today that operate on tighter curves (and at higher speeds) than Acela.

The real determining factor for curve speed is superevelation. Hans-Joachim Zierke has an excellent write-up on this. A good starting point is: [1].

Oh, and given the abysimal 60% on-time performance of NY-Boston Acela, the article should be careful in claiming a 3.5hr travel time.

The problem, of course, is that the Northeast Corridor ISN'T superelevated for the speeds they'd like to achieve with the Acela. Tilting at least allows for passenger comfort, if not ideal operation of the trains-as-a-whole.

Atlant 22:41, 3 Apr 2005 (UTC)

If the NEC isn't superelevated for higher speeds, then using a tilt train won't fix that fundamental problem. As for passenger comfort, conventional trains throughout the civilized world (well, Europe at least) commonly run at higher speeds and through the same radius as found on the NEC. Moreover, tilt trains are more expensive to purchase and maintain, so they are not an "ideal operation" either. Like I said, there was no rational engineering reason for using a tilt train.

Emccaughrin 3 Apr 2005

I'm not sure I understand your point. No, tilt-trains won't reduce the forces on the wheels/wheel-flanges/track that could be "zeroed out" by correct superelevation. But yes, tilt-trains will zero-out the forces on the passengers that are caused by incorrect superelevation by causing the carbodies to bank at the correct (coordinated) angle, and they can do this at a variety of speeds-around-the-curve rather than at just at one designed-for speed. So yes, as I stated, tilt-trains are a rational response to the demands for passenger-comfort. Whether that was worth the money is another debate, of course.

Atlant 12:28, 4 Apr 2005 (UTC)

Given the huge number of modern NON-tilt trains running on a daily basis in places like France, Switzerland, Germany through higher curve speeds than Acela, it is very hard to make the case that there was a passenger-comfort issue -- unless you think the laws of Physics are different in Europe, or an American passenger is somehow different than a European. Furthermore, it has been reported on various rail-foamer newsgroups that the tilt mechanims on Acela has frequently cut out and as far as anyone knows, passengers never noticed the difference.

Incidentally, the entry also claims that Acela captured "nearly half" of the Boston-New York market. The latest data I've seen (2003) showed it has dropped to 37%. However, the "nearly half" claim might still hold for New York-Washington.

Emccaughrin

You're arguing at cross-purposes with yourself. The European trains you reference are probably running on trackway that is correctly superelevated for the speeds at which the train is travelling, hence no need for the tilt mechanism.

No, the comparison is ROW with same superlevation through the same radius. Apples vs. apples. -EM

I also wonder why this is such a big deal with you; are you trying to prove the point that the money spent on the tilting mechanism was wasted? If so, fine; "it was wasted". We should have built a TGV-class dedicated trackway with TGV-style trainsets running at 300 kph. But we're the United States and we don't "do" rail, so we consider ourselves lucky to have gotten the Acela, such as it is.

If your point is something else, perhaps you should make it plain.

Atlant 17:02, 4 Apr 2005 (UTC)

The "point" is accuracy in the Wiki entry. -EM

I guess I've lost your point again, then. There's no doubt that tilt-train technology can provide a better passenger ride than the equivalent ride on an track which is incorrectly-superelevated for the current train speed. You haven't provided us with any facts that argue against this, nor do your European examples of acceptable rides argue against the concept of better rides. If you'd like to advance the claim in the article that the tilt-train technology was a waste of money, go ahead; edit it in and we'll see who supports your claim and who rejects your claim. If you'd like to argue that the tilt-train technology is often broken, go ahead. If the fact that the tilt-train technology's tilt-angle was limited by errors in the loading gauge and that's not already in the article, go ahead and edit that in, too. But there's nothing wrong with the tilt-train technology, in principle.

Here's the claim the article actually makes:

These trains also tilt to negotiate the many curves on the densely populated route, permitting better passenger comfort and lower construction costs for the higher speeds.

Note the use of the word better with regard to comfort and lower with regard to construction costs. Both of these claims are true facts, supported by the physics of the situation. A train that is more-closely banked to the correct angle (whether through superelevation or through tilt-train technology) is more comfrtable than a train where the turns are not approrpiately coordinated. And the roadbed construction costs (to do no special superelevation) are certainly lower than the roadbed construction costs to reconstruct all the turns to have the correct superelevation angle for the Acela Express.

Atlant 19:37, 4 Apr 2005 (UTC)