200MPH+ on the NEC: Is it practical?

[Seaboarder3023]

No one has mentioned it (though it may not even be a problem), but what about the different power systems? North of New Haven is newer ~25 year old catenary built to 60hz standards, but south of NH is much older (~90 year old) catenary built to 25hz standards. Does the older catenary/power standard affect speed at all?

 

[cirdan]

Lastly, one issue that impacts trip time is that there is no sense of urgency with Amtrak trains. We spend billions to save a minute or two, but if focused on training the Amtrak staff to run their station stop procedures like an elite commuter agency would, they would save 1,2,3,4+ minutes per stop without changing a darn thing to infrastructure.

There are also soft time savings. Just streamlining the boarding procedure (and stop pretending you're an airline) would take several minutes off effective end-to-end journey times at a considerably lower cost than squeezing the same minutes out of infrastructure and schedules.

 

[AmtrakMaineiac]

No one has mentioned it (though it may not even be a problem), but what about the different power systems? North of New Haven is newer ~25 year old catenary built to 60hz standards, but south of NH is much older (~90 year old) catenary built to 25hz standards. Does the older catenary/power standard affect speed at all?

More the catenary structure itself than the power standard. The older variable tension catenary design does limit speeds. With modern multi voltage/ frequency locomotives the 25hz power is less of an issue. In Europe they use 16.7Hz catenary at high speeds e.g. Germany.

 

[MARC Rider]

There are also soft time savings. Just streamlining the boarding procedure (and stop pretending you're an airline) would take several minutes off effective end-to-end journey times at a considerably lower cost than squeezing the same minutes out of infrastructure and schedules.

What boarding procedure slows things down? Except at the terminals, passengers are already on the platform when the train comes in, and at New York they have to line people up in the concourse because the platforms are narrow. It's true that the long-distance trains running on the NEC have long station stops because the coach attendants are fussing with assigning seats on the platform, but that doesn't happen with the Northeast Regionals or Acelas. The one thing they could do is have assigned seating on all trains with the car numbers clearly marked on the platforms so people can position themselves and line up in the right place to quickly board the train when it comes in. They do that on the Acela already, and I've experienced very short station stops as a result.

 

[cirdan]

What boarding procedure slows things down? Except at the terminals, passengers are already on the platform when the train comes in,

For the passenger, avoidable delays don't begin when the train draws into the platform, but they begin when the passenger arrives on the station sites and any obstacles to getting onto the platform may kick in.

It seems to me that many multiple millions are spent to shave just a few minutes off schedules, but inefficiencies in passenger handling are just accepted as a necessary evil.

It seems to me there is a lack of holistic thinking here.

 

[user 13416]

What boarding procedure slows things down? Except at the terminals, passengers are already on the platform when the train comes in, and at New York they have to line people up in the concourse because the platforms are narrow. It's true that the long-distance trains running on the NEC have long station stops because the coach attendants are fussing with assigning seats on the platform, but that doesn't happen with the Northeast Regionals or Acelas. The one thing they could do is have assigned seating on all trains with the car numbers clearly marked on the platforms so people can position themselves and line up in the right place to quickly board the train when it comes in. They do that on the Acela already, and I've experienced very short station stops as a result.

Many NER stops, especially south of WAS, have low platforms and only one or two doors open, and passengers have to climb down the narrow, steep steps to the platform, and then boarding passengers have to climb up. It takes a long time to board this way. Even between WAS-PHL, not all doors open at all stops. All the time I hear them announce "Only exit at the Cafe Car". High platforms would shorten the RVR stop from the current 10-15 minutes down to 1-2 minutes.

 

[west point]

Do not spend the extra money for a few miles of 200 MPH. More time will be saved just getting rid of slow sections at less cost.

 

[George Harris]

No one has mentioned it (though it may not even be a problem), but what about the different power systems? North of New Haven is newer ~25 year old catenary built to 60hz standards, but south of NH is much older (~90 year old) catenary built to 25hz standards. Does the older catenary/power standard affect speed at all?

More the catenary structure itself than the power standard. The older variable tension catenary design does limit speeds. With modern multi voltage/ frequency locomotives the 25hz power is less of an issue. In Europe they use 16.7Hz catenary at high speeds e.g. Germany.

16.7Hz is not correct by the way; it is 50Hz divided by 3, so it is 16 2/3 Hz. Normal AC in Europe is 50 Hz, not 60 Hz as in the US, Canada and quite a few other places. The history of the why for the old Pennsy's 25 Hz, I don't know. Likewise, I have no idea why the ex New Haven 11.5 kV 25 Hz was converted to 12.5 kV 60 Hz and the ex Pennsy side was not. I would suspect that the New Haven side when changed was not changed to be 25 kV to match the new electrification north of New Haven due to electrical clearance issues.

People with greater knowledge of things electrical please feel free to correct me, but I do not think frequency is that big an issue. Contact wire voltage is. If you can feed 25 kV electrically that is more efficient. Smaller voltages require larger wire sizes to carry the same amperage. Constant tension catenary also solves lots of problems. This comes under the heading of "Why did we not think of this a lot sooner?"

 

[cirdan]

I believe the origins of 25Hz is in steel mills, many of which in the past also used this frequency for their equipment. There were plenty of steel mills in Pennsy-land back in the day and the Pennsy could thus basically build on a tried and proven technology and use a certain number of off the shelf parts rather than having to reinvent the wheel for every little detail. Then why did the steel mills adopt 25Hz? In the early days of large AC motors, commutation-induced arcing was a problem, which was why low frequencies were chosen. As motor technology advanced, higher frequencies became possible. But standards, once established, tend to last a long time. Although there were earlier examples, railway electrification at higher frequencies did not become a big thing until post WW2.

Voltage frequency has no tangible effect on catenary design that I can see. High speed differs from regular catenary in the arrangement of dampers that suppress mechanical oscillation of the wire. If these oscillations are not adequately mitigated, they could lead to intermittent loss of contact pressure for the pantograph or even intermittent total loss of contact . These damping needs affect distance between supports and also counterweights and spring/elastic elements.

 

[AmtrakMaineiac]

16.7Hz is not correct by the way; it is 50Hz divided by 3, so it is 16 2/3 Hz.

16 2/3 vs 16.7 hz. From Wikipedia:
"The first generators were synchronous AC generators or synchronous transformers; however, with the introduction of modern double fed induction generators, the control current induced an undesired DC component, leading to pole overheating problems. This was solved by shifting the frequency slightly away from exactly ⅓ the grid frequency; 16.7 hertz was arbitrarily chosen to remain within the tolerance of existing traction motors."

 

[railiner]

But standards, once established, tend to last a long time.

Probably boils down to cost/benefit ratio...is it "worth it" to upgrade?

 

[JamesWhitcombRiley]

Track and catenary improvements that save minutes are usually just backlogged state of good repair work. It's quite a long list.

I wonder if Amtrak will ever buy, or trade for, or claim, Metro-North Railroad's mileage.

 

[UserNameRequired]

…

People with greater knowledge of things electrical please feel free to correct me, but I do not think frequency is that big an issue. Contact wire voltage is. If you can feed 25 kV electrically that is more efficient. Smaller voltages require larger wire sizes to carry the same amperage. …

I am going to guess you mean smaller voltages require larger wire sizes to carry the same power? P=VI

On a side note, I live in an older farm house. The previous owner told me they used to have 25hz power to the house requiring 25 hz appliances such as the refrigerator. We are somewhat near an old power generating station location long retired for an electrified line and the surrounding areas were wired into these stations.

 

[George Harris]

16 2/3 vs 16.7 hz. From Wikipedia:
"The first generators were synchronous AC generators or synchronous transformers; however, with the introduction of modern double fed induction generators, the control current induced an undesired DC component, leading to pole overheating problems. This was solved by shifting the frequency slightly away from exactly ⅓ the grid frequency; 16.7 hertz was arbitrarily chosen to remain within the tolerance of existing traction motors."

O Kkkkkkk. Duly noted. First time I heard this.

 

[west point]

PRR actually started out as 11 kV 25 hZ. (Safe Harbor). Sometime after WW-2 PRR raised it to 11.5 kV. Amtrak sometime in the 1980s raised the voltages to 12.0 kV. Each rise of course allowed the then current catenary to provide more power with same size contact wire. Now all these numbers are actually nominal with extremes +/- 10 % and desired +/- 5%. If the voltage gets too near the high amount on a section of catenary, the regeneration feature reverts to dynamic braking instead.

My understanding is that MNRR went to 12,5 kV catenary was due to insufficient clearances on the many New Haven catenary and signal bridges that would have had to been raised or replaced.

Also, as others posted the distance between catenary holders has to be shorter with higher speeds that can cause loss of contact by the pantograph. Straight track PRR standard was 180 feet. The replacement sections for constant tension is nominally 120 feet. That is one reason the higher cost than expected converting to constant tension has occurred. Note I use to observe GG1s have separation arcs often between WAS - PHL. Those arcs often caused static outbursts on my VHF radios.