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FRA Tier II speed upgrade: 150mph to 160mph


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#41 PRR 60

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Posted 09 October 2018 - 11:53 AM

Despite the PR about the speed increase, in my opinion this project was intended primarily to reinforce the electric power supply in the North Jersey segment of the NEC.  The work included added capacity at the Metuchen frequency converter, a new substation at Hamilton and various other improvements designed to solve chronic catenary voltage issues along that section of the NEC. The catenary work was an adjunct to that.

 

The problem with increasing train speed is the need for shorter catenary span lengths.  The span length issue is not due to structure strength but the need to limit catenary movement created by the pantographs at speed.  The longer the span, the greater the catenary movement (by a square factor).  The existing PRR spans are in the 225-250 foot range. Those spans, originally designed for 80 mph operation, are right at the limit for 135 mph (if not longer than ideal).  Spans in the 150-175 foot range are needed for higher speeds.  In order to get shorter spans where there are now longer spans, new structures are needed and a lot of them.  A 23-mile section of railroad would need about 700 new catenary structures.  At about $200,000 each, that is $140 million just for structures.  Given the logistical complexity of installing new structures on the NEC with very limited work windows due to traffic and power constraints, that estimate could be low.

 

I have no inside knowledge, but my guess is that the desire for higher speed lost out to the fiscal reality of the expenditure needed to achieve higher speeds.  There will be a segment with constant tension and shorter spans, but some of the original catenary replacement work is now limited to hardware replacement on the existing structures while retaining the fixed termination design.

 

The completion of the power supply enhancements will fulfill the primary goal of the project.


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#42 jis

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Posted 09 October 2018 - 12:04 PM

Also the complete rebuilding of Midway Interlocking with high speed crossovers, the construction of new crossover interlockings Delcon and Adams and increasing track speed to 125mph on tracks 1 and 4 between County and Ham together with replacement of the signaling system including changes in block lengths, all this together increases speed of all non-Acela trains and increases throughput capacity irrespective of what finally comes of the catenary work.

 

One thing that I have wondered about is that they did not have to change spans just to convert to constant tension, which in and of itself brings advantages. MNRR did not in general change span lengths in converting to constant tension.

 

I think what happened is that they slapped together a proposal quickly, without much detailed planning of what was necessary for which segment to meet a proposal deadline thrown at them by FRA when Scott returned the money. After that they slowly figured out that east of Midway they could not get speed limits upto where CT is necessary and punted on the thing there. Then they badly botched the project west of Midway and finally managed to install shorter span CT for about half the planned distance, and completely punted on CT everywhere else. Also, for some unknown reason, or reason I don;t understand, they opted for a three wire system even for the shorter span segments, where the rst of the world manages fine with two wire systems. Apparently cost containment was not one of the over-riding goals of the original plan.

 

Anyway, now that is much water under the bridge, until the next screwup I suppose. Cynic? Moi?


Edited by jis, 09 October 2018 - 01:01 PM.

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#43 Ryan

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Posted 09 October 2018 - 05:54 PM

The problem with increasing train speed is the need for shorter catenary span lengths.  The span length issue is not due to structure strength but the need to limit catenary movement created by the pantographs at speed.  The longer the span, the greater the catenary movement (by a square factor).  The existing PRR spans are in the 225-250 foot range. Those spans, originally designed for 80 mph operation, are right at the limit for 135 mph (if not longer than ideal).  Spans in the 150-175 foot range are needed for higher speeds.

 
 

One thing that I have wondered about is that they did not have to change spans just to convert to constant tension, which in and of itself brings advantages. MNRR did not in general change span lengths in converting to constant tension.


I wonder (and I am neither an engineer, nor did I stay at a Holiday Inn last night) how catenary tension figures into the equation.

I would assume (recalling back to High School physics) that with higher tension, you would get less catenary movement (holding span length and speed constant). If that assumption is correct, then it would stand to reason that with constant tension catenary, you would avoid the low tension wires when it was hot outside (and many thanks to Jishnu for explaining that to me not long after I showed up here over 10 years ago), the overall speeds could be improved.

Empirically, this seems to be born out in the examples in Jishnu's post.
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#44 west point

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Posted 09 October 2018 - 06:52 PM

Granted the shorter span lengths call for a lot more spans.  However there are reports that the original spans are having major corrision problems at the point where the span pole enters the earth.  Since poles are going to be needed to be replaced placing 3 span poles where 2 are at present appears to be very prudent..   As for three wire CAT why remove one wire when it probably costs very little to connect to hangers. On other hand removing one wire may be costly ?  That would require redesigning hanger system ?



#45 VT Hokie

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Posted 10 October 2018 - 11:37 AM

I was just at Princeton Junction yesterday (actually took a ride from New Brunswick down and back to capture the 'ol Turboliners!   ) and it looks like they're doing work on track 3 with constant tension in place on the other tracks already.  It's unfortunate to hear of the cost overruns and scale backs, but I can't believe they're doing all this work for nothing.  The non-constant tension segments from roughly Jersey Ave down to Monmouth Junction and from south of Princeton Junction to Trenton have noticeable new hangars that I guess improve the rigidity of the variable tension wires.  So, I hope that means that those will be acceleration/deceleration zones that at least allow Avelia Liberty to demonstrate its 160 mph performance for those 8 miles or so of constant tension on the Princeton Junction - Monmouth Junction stretch.

 


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#46 jis

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Posted 10 October 2018 - 11:45 AM

Avelia Liberties will be able to demonstrate their 160mph capability in RI and MA too.
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#47 Amtrak706

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Posted 10 October 2018 - 07:27 PM

Speaking of 160mph, does anyone happen to know the answer to my original question? Lol

#48 cpotisch

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Posted 10 October 2018 - 07:29 PM

Speaking of 160mph, does anyone happen to know the answer to my original question? Lol

 

This one? 

Did Amtrak ever get a response on their petition to increase FRA Tier II speeds to 160 mph for the County to Ham upgrade?


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#49 Amtrak706

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Posted 10 October 2018 - 07:32 PM

Yes.

#50 daybeers

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Posted 10 October 2018 - 07:34 PM

From a reliable source on a similar thread over on Railroad.net:

 

It should be done by the end of this year/start of next year but there probably wont be a speed change, and they only completed the constant tension upgrade for about 8 miles vs the 13 or so they were supposed to do. All because catenary poles were not going up fast enough.

Is this confirmed?


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#51 VT Hokie

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Posted 10 October 2018 - 10:35 PM

I assume that they'll add in the "enhanced variable tension" catenary supports where they failed to install constant tension, as seen here in Hamilton.  Again, I can't imagine they spent all this money and did all this work for nothing, but then on the other hand, this is Amtrak we're talking about - the same Amtrak that's sending the rebuilt Turboliners to the scrapper after getting no use out of 'em, and that spent a couple billion on the Chicago - St Louis route only to stay stuck at 79 mph with 110 mph always seemingly promised for "next year" for at least the last five years, and that's currently using the new Viewliner dining cars to serve cold snacks in a box.  So, I guess anything is possible.

http://www.railpictu...t/photo/657488/


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#52 jis

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Posted 11 October 2018 - 09:32 AM

I guess it is impossible to get through to people that even if there is no speed increase a very significant part of the investment was not for nothing. Afterall minds are made up. Why get confused with facts. That is afterall the fashion of the day.

This is not to say there was not a massive screwup with the catenary project. I am the one that has been reporting on it. But let us also not get carried away with the negative extravaganza
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#53 PRR 60

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Posted 11 October 2018 - 09:57 AM

I guess it is impossible to get through to people that even if there is no speed increase a very significant part of the investment was not for nothing. Afterall minds are made up. Why get confused with facts. That is afterall the fashion of the day.

This is not to say there was not a massive screwup with the catenary project. I am the one that has been reporting on it. But let us also not get carried away with the negative extravaganza

 

Just to briefly explain the third wire in the PRR catenary that continues to be in place with the rebuild.  That wire, located immediately above the trolley (contact) wire is called the "auxiliary."  It is a high-conductivity, copper wire (originally solid 4/0) that is used to provide current capacity in the catenary system.

 

The other two wires in the catenary, the sagged "messenger" and the trolley wire are high-strength bronze and a special copper alloy and are not great electrical conductors. Those two combined do not have the capacity to supply the load between the substations and catenary supply taps, located about every eight miles.  The auxiliary provides that capacity.  In order to eliminate the auxiliary wire, another means to provide capacity or limit load would have to be provided such as locating catenary feeder conductors somewhere else on the structures (tapped to the catenary every couple of miles).  My guess is that the easiest solution was to replace the auxiliary wire in-kind.

 

As a contrast to the PRR system, the New Haven to Boston electrification is 25kV and has catenary feeds every six miles.  That is the electrical equal to having 12kV feeds every three miles.  The north end electrification does not need an auxiliary wire for current capacity. The south end does.


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#54 bretton88

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Posted 11 October 2018 - 10:20 AM

I assume that they'll add in the "enhanced variable tension" catenary supports where they failed to install constant tension, as seen here in Hamilton.  Again, I can't imagine they spent all this money and did all this work for nothing, but then on the other hand, this is Amtrak we're talking about - the same Amtrak that's sending the rebuilt Turboliners to the scrapper after getting no use out of 'em, and that spent a couple billion on the Chicago - St Louis route only to stay stuck at 79 mph with 110 mph always seemingly promised for "next year" for at least the last five years, and that's currently using the new Viewliner dining cars to serve cold snacks in a box.  So, I guess anything is possible.

http://www.railpictu...t/photo/657488/

One minor nitpick, the state of Illinois is in charge of that disaster that is the Chicago to St Louis project.
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#55 jis

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Posted 11 October 2018 - 10:33 AM

PRR you are quite right. I keep forgetting that the PRR electrification is not modern 25kV 60Hz, which allows feeders to be spaced much further apart, specially if 2x25kV is used for the feeder. That is the primary reason that most of the modern systems are two cable systems. Many though also have a third return cable strap connected to the track, to keep stray current from getting into stuff causing problems around the track.



#56 ehbowen

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Posted 11 October 2018 - 11:49 AM

I'm going to be the major opposing opinion here; but I really don't see the point in raising the speed limit at all.

...

So in my opinion 150 to 160 is just a waste of time, and money.

 

George Harris (internet acquaintance and civil engineer who has worked on rail projects from Washington Metro to Taiwan HSR and CA-HSR) is wont to say, "The best way to go fast is to avoid going slow." In other words, you will get much more bang for the buck in raising a 60 MPH speed restriction to 90 MPH than you will by increasing a 150 MPH top speed to 160 MPH. Baltimore tunnels, anyone?


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#57 jis

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Posted 11 October 2018 - 12:15 PM

That is absolutely true, and what is also true is that trying to do anything with Baltimore Tunnels, North Philly through Philly or Wilmington are all individual billion plus projects. Big bucks with big bangs. But with the inability to scare up the bucks, one tends to do things opportunistically when bits of money become available, where you get a whole bunch of SOGR work done and incidentally get a speed increment from 135 to 150. The 150 to 160 increment has very little added cost associated specifically with it. Most of the additional cost is already eaten up in the catenary and signaling and track realignment work for 150, SOGR, added reliability and throughput.

 

Another incremental piece of work worthy of funding is the Midline Loop to decongest County interlocking and get NJT Jersey Avenue Service out of the way of the main line. It does not increase the speed of anything but removes conflicts which should on an average improve schedule reliability and net average speed through the congestion point.


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#58 west point

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Posted 12 October 2018 - 01:04 PM

Another item of changing the PRR CAT to constant tension.  Most locations PRR CAT as built has connection wire(s) between the vertical poles on opposite sides of all tracks.  Suspended from this connection wire(s) usually is the messenger wire for all tracks.  In the case of Trenton north it is 4 tracks occasionally more.  Whenever a train's PAN tangles with the trolley wire many time the PAN pulls down the messenger wire as well for its track and also the other track's messenger wires as well taking all tracks out of service.

Constant Tension as being built for the PRR sections instead has a horizontal beam crossing across all tracks to the vertical poles on both sides of all tracks.  Suspended from this horizontal beam is a hanger that holds the messenger just for that track so each beam has at least four hangers one each for each track. Note the hanger can move slightly due to the various temperatures of wire. Therefore snagging the trolley wire only pulls down the wire for that track.  Of course occasionally wire from one track might foul wire for tracks next to wire down.  Still repair is much faster and traffic is not stopped.

Since it appears the NJT snags the trolley wire much more ( maybe as EMU trains have up to 6 PANs ) this constant tension will allow Amtrak to continue running except in vicinity of a snagged wire .     

Another factor is PRR CAT has all tracks connected electrically where as the Constant tension can be isolated for each track except at interlockings.  If that is being done that would increase the costs significantly as many more CBs / control switches will be needed for each track  ? ?


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#59 jis

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Posted 12 October 2018 - 02:04 PM

AFAICT all that is being done is replacing variable tension with constant tension with absolutely no9 change made to the overall layout of the feeding system, other than to add more converter capacity. They are adding/have added substations to enhance power capacity, but they are not isolating individual track catenaries anymore than they already are or not.



#60 west point

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Posted 12 October 2018 - 08:23 PM

JIS Have you observed the work to see that individual feeders to each track are not in sight  ?   Could it be that individual feeders are in place but are connected together ?  Since have no plans to visit anytime soon will have to use your best observations ? 






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