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Re: The Last SP Train #75, The Lark April 8, 1968 at LA
Author: OldPoleBurner
Date: 01-01-2010 - 18:30
I also agree with Sgt. Joe here. As America re-trenches back into a more sensible reality (assuming it continues to do so), such things are inevitable. And most people will probably like it better anyway.
But what would help hasten the day more than almost anything else, would be to speed the dang trains up a bit. Or a lot - actually! Amtrak's almost thirteen hour schedule Emeryville (SF connection) to LA is patently absurd. Compare that to SP's Sept 1950 9-3/4 hour schedule, which it faithfully kept; or current six to seven hour highway times.
Amtrak's current scheduling is an embarrassment. Faster was obvious done before, with steam and only simple ABS and train orders yet. And with a lot more trains on the line too. If it can be done without the benefit of fancy modern technology railroads now have; then why can't it be done now. Or is some of that fancy new stuff actually the cause of some of that embarrassment!
Never mind - If it was ever done, then it obviously can be done! Whatever it is that is in the way, maybe ain't worth it - get it out of the way. We are kidding ourselves to think we will ever get decent ridership on even one SF to LA train, let alone two, with such a ridiculously slack schedule.
But going a bit faster than the schedules of 60 years ago, would help rail compete even better. However, what actually kept SP's trains from attaining a 6-3/4 hour schedule over the 470 mile route, at a 79mph maximum, was the hundreds of curve speed restrictions that plague the line; as they do nearly all rail lines.
The good news is, that one piece of technology that wasn't available to the SP 60 years ago - is available now, and is already in use commercially several places worldwide, including the United States.
Given that curve speed restrictions for passenger trains are calculated to limit lateral forces on the passenger's seat of the pants; the resulting speed limit on curves is only about half the calculated safety limit (turnover speed). Trains could actually go nearly twice as fast around curves (signal blocks and rail structure being adjusted for it) without compromising safety. It would be however, a very unpleasant ride without some way to reduce those lateral forces.
Further aggravating curve speed restrictions, is the fact that all rail cars tend to tilt even further outward on curves, adding a lot to the discomfort. The higher the center-of-gravity (think double decker), or the softer the springs, the worse that gets. These tendencies must be measured and accounted for in the engineering equations that determine speed limits (they actually are vehicle specific).
Keeping the ride comfortable requires keeping lateral forces near equilibrium. Primarily, super-elevation on curves (banking) is used to counteract those lateral forces and the tilt out which aggravates the perception of them; but that technique is severely limited by many practical engineering considerations, which are way beyond the scope of this article. Suffice it to say - limitations on the practicality of super-elevating the track, translates directly into severe limitations to the overall speed of passenger trains.
On the other hand, proactively tilting the car inward as it enters a curve, totally overcoming the tendency to tilt out; while also adding inward tilt to overcome even more centrifugal force, will allow a great speed-up. With trains able to go around curves as fast or faster than automobiles, they will become quite competitive.
Such technology would entirely overcome curvature restrictions on existing track, making a 79mph 6-3/4 hour 8 stop schedule quite realistic, and at relatively small cost. And combined with the much shorter braking distances afforded by electric brake controls, most existing signal spacings would already be adequate.
YES - I know it ain't the favorite pipe dream buzzword of late - "High Speed Rail". But at this point in our currently rail-less history, does it really need to be?
Why don't we get our grabby hands out of the proverbial cookie jar, with something actually do-able with the resources we actually have. It will quickly spark a dramatic change in the transportation landscape. It would not be unreasonable to imagine taking 30% of the ground transportation market with just such a speed up. It's a freeek'nnnn no brainer! - - -
OPB
P.S. - Now - with imagination really flowing - just imagine CZ like dome cars fitted with tilt technology - plying the coast!. And crammed full of people that used to drive SF to LA, but wouldn't even think of doin' it now. What a breath taking ride that would be!
But what would help hasten the day more than almost anything else, would be to speed the dang trains up a bit. Or a lot - actually! Amtrak's almost thirteen hour schedule Emeryville (SF connection) to LA is patently absurd. Compare that to SP's Sept 1950 9-3/4 hour schedule, which it faithfully kept; or current six to seven hour highway times.
Amtrak's current scheduling is an embarrassment. Faster was obvious done before, with steam and only simple ABS and train orders yet. And with a lot more trains on the line too. If it can be done without the benefit of fancy modern technology railroads now have; then why can't it be done now. Or is some of that fancy new stuff actually the cause of some of that embarrassment!
Never mind - If it was ever done, then it obviously can be done! Whatever it is that is in the way, maybe ain't worth it - get it out of the way. We are kidding ourselves to think we will ever get decent ridership on even one SF to LA train, let alone two, with such a ridiculously slack schedule.
But going a bit faster than the schedules of 60 years ago, would help rail compete even better. However, what actually kept SP's trains from attaining a 6-3/4 hour schedule over the 470 mile route, at a 79mph maximum, was the hundreds of curve speed restrictions that plague the line; as they do nearly all rail lines.
The good news is, that one piece of technology that wasn't available to the SP 60 years ago - is available now, and is already in use commercially several places worldwide, including the United States.
Given that curve speed restrictions for passenger trains are calculated to limit lateral forces on the passenger's seat of the pants; the resulting speed limit on curves is only about half the calculated safety limit (turnover speed). Trains could actually go nearly twice as fast around curves (signal blocks and rail structure being adjusted for it) without compromising safety. It would be however, a very unpleasant ride without some way to reduce those lateral forces.
Further aggravating curve speed restrictions, is the fact that all rail cars tend to tilt even further outward on curves, adding a lot to the discomfort. The higher the center-of-gravity (think double decker), or the softer the springs, the worse that gets. These tendencies must be measured and accounted for in the engineering equations that determine speed limits (they actually are vehicle specific).
Keeping the ride comfortable requires keeping lateral forces near equilibrium. Primarily, super-elevation on curves (banking) is used to counteract those lateral forces and the tilt out which aggravates the perception of them; but that technique is severely limited by many practical engineering considerations, which are way beyond the scope of this article. Suffice it to say - limitations on the practicality of super-elevating the track, translates directly into severe limitations to the overall speed of passenger trains.
On the other hand, proactively tilting the car inward as it enters a curve, totally overcoming the tendency to tilt out; while also adding inward tilt to overcome even more centrifugal force, will allow a great speed-up. With trains able to go around curves as fast or faster than automobiles, they will become quite competitive.
Such technology would entirely overcome curvature restrictions on existing track, making a 79mph 6-3/4 hour 8 stop schedule quite realistic, and at relatively small cost. And combined with the much shorter braking distances afforded by electric brake controls, most existing signal spacings would already be adequate.
YES - I know it ain't the favorite pipe dream buzzword of late - "High Speed Rail". But at this point in our currently rail-less history, does it really need to be?
Why don't we get our grabby hands out of the proverbial cookie jar, with something actually do-able with the resources we actually have. It will quickly spark a dramatic change in the transportation landscape. It would not be unreasonable to imagine taking 30% of the ground transportation market with just such a speed up. It's a freeek'nnnn no brainer! - - -
OPB
P.S. - Now - with imagination really flowing - just imagine CZ like dome cars fitted with tilt technology - plying the coast!. And crammed full of people that used to drive SF to LA, but wouldn't even think of doin' it now. What a breath taking ride that would be!
