Acela Speeds

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Re: Acela Speeds

Postby jwhite07 » Wed Sep 27, 2017 11:23 am

The trip I took was in August of 1990. I don't remember how busy the train was overall, but I did have the two-seater to myself the whole way, except for a fair bit of time when one of the trainmen noticed I was reading a railfan magazine and sat down next to me for a chat and to point out a few things of train-buff interest along the way. Couldn't have been all that busy if he could do that!
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Re: Acela Speeds

Postby ApproachMedium » Wed Sep 27, 2017 11:38 am

The poles being closer together has little to do with speed, it has to do with the constant tension catenary sections. There are already some improvements from the upgrades, but not from the wire/catenary sections. As of right now we have only seen the benefits of the new progressive high speed signal system that was installed along the way. The system has greatly improved the following of trains on the same track since the system can give you i think 5 different cab aspects vs the previous 3. You now can get clear, cab 80, approach medium, approach and restricting where before it was clear, approach (30mph) and restricting. So youd get up to 110 or 125 and then get too close to a train and bam, cab drops to approach. Put the brake on, do 30 for a mile, it comes up, speed up, drops again. Now you can usually follow an NJT train at 80 or 45 depending and not drop to such low speeds. It really keeps the trains moving.
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Re: Acela Speeds

Postby gokeefe » Wed Sep 27, 2017 1:21 pm

Wow that was awful. I never would have imagined that the system would have been setup so tightly.
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Re: Acela Speeds

Postby ExCon90 » Wed Sep 27, 2017 3:09 pm

Regarding the posts above about the nonstop Metroliner, true--that Metroliner was leaving NCR with empty seats. On a historical note, Baltimore enacted an ordinance around the time the Union and B&P Tunnels were built requiring all trains operating through Baltimore to make a station stop in that city, and the City Council blew the dust off the ordinance and started to make difficulties over that nonstop Metroliner, but the situation resolved itself when Amtrak discontinued the nonstop to fill seats. I suppose the issue could be raised again if nonstop Acelas were introduced, but I don't see a city ordinance overriding interstate-commerce implications. They'd have to try to make a safety issue out of it.
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Re: Acela Speeds

Postby bostontrainguy » Wed Sep 27, 2017 8:19 pm

What about the section in Massachusetts or Rhode Island where they also tested for 160 mph? That is modern constant-tension catenary. Are those stretches capable of handling the higher speeds without additional modification? Why hasn't it been done?
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Re: Acela Speeds

Postby ApproachMedium » Wed Sep 27, 2017 11:13 pm

Design speed for the acela is 160mph. They have always accounted for 10mph grace over top speed, in case of speedometer inaccuracies etc. With modern electronics that is not as necessary. Anyhow the track is maintained to achieve that speed as well as the wire but the signal systems top speed is programmed at 150. They could change it, but im not sure they are going to until the new train sets come out which will have a higher top speed.
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Re: Acela Speeds

Postby bostontrainguy » Thu Sep 28, 2017 9:21 am

So these stretches in New England could have been used as a test bed for 160 mph without any modification. Wouldn't that have been the better choice?
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Re: Acela Speeds

Postby east point » Thu Sep 28, 2017 12:43 pm

Wonder if NE stretches not long enough for the sustained speed tests ? Another item might have been testing the variable tension CAT ( PRR ) at those speeds to verify how that CAT behaved at those speeds ? If it had passed then constant tension might not have been required for 160 ? Wasn't the fastest recorded speed 171 MPH ?

Then again there may ( probably ) have been other measurements. Wheel rail interaction, car action under that class of track ( PRR ) which has an older base and subgrade, PAN bounce, Operation under 25 hZ 12 kV compared to previous tests under 25 kV 60 hZ ? etc.
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Re: Acela Speeds

Postby Matt Johnson » Thu Sep 28, 2017 3:23 pm

east point wrote:Wonder if NE stretches not long enough for the sustained speed tests ? Another item might have been testing the variable tension CAT ( PRR ) at those speeds to verify how that CAT behaved at those speeds ? If it had passed then constant tension might not have been required for 160 ? Wasn't the fastest recorded speed 171 MPH ?

Then again there may ( probably ) have been other measurements. Wheel rail interaction, car action under that class of track ( PRR ) which has an older base and subgrade, PAN bounce, Operation under 25 hZ 12 kV compared to previous tests under 25 kV 60 hZ ? etc.


During early Acela testing the train reached an official max of 168.8 mph near Kingston, Rhode Island. During more recent testing through the Princeton Junction, New Jersey area, the Acela is unofficially reported to have exceeded 170 mph, likely breaking the UA Turbo record but alas, not officially recorded as doing such.

The Avelia Liberty will be 186 mph capable in the tilt version (with the potential for a 220 mph variant). I wouldn't be surprised to see it smash the existing records during testing through Princeton Junction!
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Re: Acela Speeds

Postby Nasadowsk » Thu Sep 28, 2017 5:29 pm

Matt Johnson wrote: I wouldn't be surprised to see it smash the existing records during testing through Princeton Junction!


I would - most HSTs have pretty awful acceleration rates, being geared for such high speeds. The run through there isn't very long and you might not be able to get to full speed before you hit the next speed restriction...
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Re: Acela Speeds

Postby ApproachMedium » Thu Sep 28, 2017 8:49 pm

bostontrainguy wrote:So these stretches in New England could have been used as a test bed for 160 mph without any modification. Wouldn't that have been the better choice?


No because the sections up there are double track. The seconds down in NJ are 4 track and Amtrak dispatches the lines. So we have good control where they could close the two middle tracks and run testing while keeping the two outside tracks open for regular traffic during the over night. It is essential that no other trains pass the high speed test run on the other high speed track because of the wire movement in the crap tensioned PRR cat wire. With the excessive bounce you could cause pantograph damage at those speeds.
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Re: Acela Speeds

Postby johndmuller » Thu Sep 28, 2017 11:44 pm

ApproachMedium wrote:
The system has greatly improved the following of trains on the same track since the system can give you i think 5 different cab aspects vs the previous 3. You now can get clear, cab 80, approach medium, approach and restricting where before it was clear, approach (30mph) and restricting. So youd get up to 110 or 125 and then get too close to a train and bam, cab drops to approach. Put the brake on, do 30 for a mile, it comes up, speed up, drops again. Now you can usually follow an NJT train at 80 or 45 depending and not drop to such low speeds. It really keeps the trains moving.

Wouldn't the same sort of thing be happening in this scenario anyway, just not with as extreme speed changes? The NJT train is still going to be there and will be setting the effective max speed; I suppose if one knew the situation, one could just go 79 or whatever NJT is doing and not have to ping pong up and down much if at all so long as there was enough separation.
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Re: Acela Speeds

Postby ApproachMedium » Sat Sep 30, 2017 8:25 pm

It doesnt work that way, eventually you get closer and you go from clear to approach. The blocks used to be very long. They are much shorter now and with the progressive block system it understands train speeds and will negotiate the cab signal indications for the train following the train ahead of it accordingly. Trust me, as an experienced engineer with both systems the new system works much better at keeping the traffic flowing even if its not at track speed. The NJT trains currently are good for 100mph and 80 for MU. They will be increasing the NJT multilevel trains to 125mph as part of the upgrades eventually. The same cars on MARC are now good for 125 and run on Amtrak B class speed tables vs C class speed tables of the previous.
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Re: Acela Speeds

Postby R36 Combine Coach » Sat Sep 30, 2017 10:28 pm

Matt Johnson wrote:The Avelia Liberty will be 186 mph capable. I wouldn't be surprised to see it smash the existing records during testing through Princeton Junction!
Westinghouse Metroliners 800 & 802 hit 175 mph on this very stretch on 12/17/67, so it is within reach.
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Re: Acela Speeds

Postby gokeefe » Sun Oct 01, 2017 9:39 am

R36 Combine Coach wrote:
Matt Johnson wrote:The Avelia Liberty will be 186 mph capable. I wouldn't be surprised to see it smash the existing records during testing through Princeton Junction!
Westinghouse Metroliners 800 & 802 hit 175 mph on this very stretch on 12/17/67, so it is within reach.


Having traveled on Acela through Kingston a few times at 150 MPH it seems so unbelievably fast to think of 175 MPH.

Hopefully Avelia Liberty will be able to operate at or very close to full capability.
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