Ride quality, axle load and track quality discussion

[jis]

That makes sense, but I was comparing it to the NEC, in particular NB to PJunct, which I dont believe has seen freight rail in decades (maybe I am wrong). Also the track on the 'raceway' is pretty new isnt it?

Only a few local delivery freights. No run through freights.

The NJT ALP45s are plenty heavy to be able to cause damage equivalent to a heavy coal car. One of the problems on the NEC is that too much of the passenger stock that runs there is quite heavy axle load.

 

[Touchdowntom9]

Only a few local delivery freights. No run through freights.

The NJT ALP45s are plenty heavy to be able to cause damage equivalent to a heavy coal car. One of the problems on the NEC is that too much of the passenger stock that runs there is quite heavy axle load.

Thought that there was only a ~25,000 pound difference between the ALP 45DP and the Siemens Charger? Is that difference really enough to tear up the tracks while the charger would not?

Also I thought many parts of the NEC used 155PS rail specifically to avoid being torn up by coal cars etc?

 

[jis]

Thought that there was only a ~25,000 pound difference between the ALP 45DP and the Siemens Charger? Is that difference really enough to tear up the tracks while the charger would not?

Also I thought many parts of the NEC used 155PS rail specifically to avoid being torn up by coal cars etc?

Even the Chargers won't be kind to the tracks, but every bit of lesser weight helps. At the end of the day all it means is that the tracks have to be maintained more frequently.

Consider this.... the typical axle load on high speed lines is between 17 and 22 tonnes (metric). Charger is ~30 tonnes. ALP45DP is ~33 tonnes.

One of the reasons they offloaded the electrical gear from the main loco to the adjacent car is to refrain from raising the axle load on the loco in the ICTs. They are working hard to see if they can shed a tonne or two per axle on the ICT Chargers. High axle load has been a major headache and a cause for rough riding of the Acela Is, and initial failure of brackets for mounting yaw dampers and such.

 

[Touchdowntom9]

Even the Chargers won't be kind to the tracks, but every bit of lesser weight helps. At the end of the day all it means is that the tracks have to be maintained more frequently.

Consider this.... the typical axle load on high speed lines is between 17 and 22 tonnes (metric). Charger is ~30 tonnes. ALP45DP is ~33 tonnes.

One of the reasons they offloaded the electrical gear from the main loco to the adjacent car is to refrain from raising the axle load on the loco in the ICTs. They are working hard to see if they can shed a tonne or two per axle on the ICT Chargers. High axle load has been a major headache and a cause for rough riding of the Acela Is, and initial failure of brackets for mounting yaw dampers and such.

I had heard the Bombardier Multilevel IIIs were causing issues with weight but given that their axle load is in that 15 ton weight range, really just seems to be an issue with the dual modes. Wish NJT had followed suit with Amtrak and offloaded some of the dual mode electric equipment from the DP into a Multilevel to save weight per axle.

 

[jis]

I had heard the Bombardier Multilevel IIIs were causing issues with weight but given that their axle load is in that 15 ton weight range, really just seems to be an issue with the dual modes. Wish NJT had followed suit with Amtrak and offloaded some of the dual mode electric equipment from the DP into a Multilevel to save weight per axle.

Actually the weight of the locomotives is related to the weight of the multi-levels In order to be able to accelerate a train of 8-10 multilevels at a reasonable rate using a single power head, to operate vaguely acceptably on a frequent stopping suburban service you require the axle load to get enough tractive effort. So it is not like merely off loading axle load would make it work unless with the axle load some tractive effort is also offloaded. That is why the axles under the panto car in the ICTs are powered. NJT should have acquired EMUs for their operating characteristics, but the geniuses at MMC bought a bill of goods served to them by Bombardier, which was quite unsuitable for their use, instead. Now they are desperately and belatedly trying to convert them into EMUs by getting enough powered multi level (MPVs) so as to create three car units consisting of one MPV and two MLVs so as to be able to accelerate reasonably. Since they have endless capital funding but not enough operating money they can fritter away gobs of money doing idiotic things.

 

[George Harris]

I could talk a while on this subject. First, since impact force is mass times acceleration, the faster you go the more force is applied to the track due to irregularities in wheels, rails, and track support. Because of this the in the early days of TGV operation, the high speed tracks began to have issues with tie deterioration and ballast pulverization under the ties similar to that which occurs under heavy axle load trains. Their standards were working fine under the usual speeds and axle loads on lower speed lines, but not so good on the high speed tracks. There was quite a bit of discussion at the time in the trade press, but "oops we goofed because we overlooked basic physics" was never mentioned. EMU versus power units and coaches: Again, a certain amount of thought would get you to EMU is the only logical way to go for high speed and frequent stopping services. You can always stuff enough power in an engine to get comfort limited acceleration at your lowest speeds and spin the wheels, and for that matter exceed the wheel to rail adhesion at higher speeds under wet rail conditions. Since adhesion is proportional to weight, you can only improve adhesion by increasing the weight on powered axles. That means either heavier loads on your power car or more powered axles, hence EMU. By the way, also adhesion decreases with speed, which makes going to EMU even more imperative for high speed trains.

 

[Touchdowntom9]

Actually the weight of the locomotives is related to the weight of the multi-levels In order to be able to accelerate a train of 8-10 multilevels at a reasonable rate using a single power head, to operate vaguely acceptably on a frequent stopping suburban service you require the axle load to get enough tractive effort. So it is not like merely off loading axle load would make it work unless with the axle load some tractive effort is also offloaded. That is why the axles under the panto car in the ICTs are powered.

Sorry in advance if I go in a few directions here:

Ok, but the 46As (which are obvy only electric) don’t seem to have any issue pulling 9 or 10 of them and weigh less than 200K pounds (yes they could be faster accelerating but still) Are you saying that because the 45s have reduced HP vs the 46As, they need to be heavier to produce enough tractive effort?

NJT should have acquired EMUs for their operating characteristics, but the geniuses at MMC bought a bill of goods served to them by Bombardier, which was quite unsuitable for their use, instead. Now they are desperately and belatedly trying to convert them into EMUs by getting enough powered multi level (MPVs) so as to create three car units consisting of one MPV and two MLVs so as to be able to accelerate reasonably.

I understand your comment regarding the EMUs being a much better option, but what would have been your suggestion for their other rolling stock that goes from electric to diesel territory if you don’t have time to wait to electrify the whole network (NJ Coast Line, Main Line etc)

In a perfect world I would assume the ideal outcome is an EMU that can use overhead Cat when available, but also be powered by an attachable engine that would send electricity to power each EMU car’s motor (the engine could be swapped out for a regular cab car in the event that it was not needed. Ideally since each car is an emu, the engine wouldn’t need to be an actual loco but just a prime mover (power pack?) But truthfully I have no clue if that is even possible or if I’m spewing nonsense.

Now they are desperately and belatedly trying to convert them into EMUs by getting enough powered multi level (MPVs) so as to create three car units consisting of one MPV and two MLVs so as to be able to accelerate reasonably.

I heard about this order and seemed promising but then I remembered I’m talking about NJT, who cant get anything right. Are you aware of any info or have an educated guess on what kind of HP the EMU MLIII EMU power cars are supposed to or need to have? Just curious how much they might need in order to provide superior acceleration to the existing ALP46A consists and if they will be remotely successful in mitigating the issues that NJT currently has.

 

[Caesar La Rock]

Sorry in advance if I go in a few directions here:

I understand your comment regarding the EMUs being a much better option, but what would have been your suggestion for their other rolling stock that goes from electric to diesel territory if you don’t have time to wait to electrify the whole network (NJ Coast Line, Main Line etc)

In a perfect world I would assume the ideal outcome is an EMU that can use overhead Cat when available, but also be powered by an attachable engine that would send electricity to power each EMU car’s motor (the engine could be swapped out for a regular cab car in the event that it was not needed. Ideally since each car is an emu, the engine wouldn’t need to be an actual loco but just a prime mover (power pack?) But truthfully I have no clue if that is even possible or if I’m spewing nonsense.

They have EMUs that can also operate on diesel power too, called DEMUs or Bi-Mode trains. Alstom I know mounts the diesel engines on the roof as seen for SNCF's Régiolis trains, which you can see for yourself in this video. No need to attach anything, switch to diesel mode and the train continues on its way.

 

[jis]

Ok, but the 46As (which are obvy only electric) don’t seem to have any issue pulling 9 or 10 of them and weigh less than 200K pounds (yes they could be faster accelerating but still) Are you saying that because the 45s have reduced HP vs the 46As, they need to be heavier to produce enough tractive effort?

EMUs would perform better than those lumbering push-pulls, specially on lines like the M&E which has very frequent stops with some very significant gradient. In bad winter days the 46s and even the 45s spend more time spinning their wheels on the Short Hills ramp than actually moving trains. I used to live by the ramp. It was at once hilarious and painful to watch.There is a reason that the French use push-pulls only on Regional trains with infrequent stops and use EMUs on subrurban trains with frequent stops.

I heard about this order and seemed promising but then I remembered I’m talking about NJT, who cant get anything right. Are you aware of any info or have an educated guess on what kind of HP the EMU MLIII EMU power cars are supposed to or need to have? Just curious how much they might need in order to provide superior acceleration to the existing ALP46A consists and if they will be remotely successful in mitigating the issues that NJT currently has.

They are planning to run 12 car trains with four MPVs so my guess would be around 2000HP. 1000HP per power pack/truck. Remember it is not just the horsepower but the effective utilization of 16 axles to transmit the power in the form of traction/tractive effort, not just 4.

I understand your comment regarding the EMUs being a much better option, but what would have been your suggestion for their other rolling stock that goes from electric to diesel territory if you don’t have time to wait to electrify the whole network (NJ Coast Line, Main Line etc)

DMUs of course. For exacly the same reasons. The whole entire rest of the world has gone that way, but we in the US have been reluctant to even fund development of such.

One thing in favor on NJT as a whole is that they did finally go with the RiverLINE DMUs, but that is not the NJT Rail Division. That is the NJT Bus Division that contracted out the entire thing in a DBMO. NJT Rial Division seems to be more attuned to operate something like a rural rail system with slow lumbering trains with a few trains each way in the morning and evening when it comes to operating their remote trackage. They can;t even satisfy the simple contractual needs that they signed with MNRR for the West of Hudson service.

 

[George Harris]

DMUs of course. For exactly the same reasons. The whole entire rest of the world has gone that way, but we in the US have been reluctant to even fund development of such.

My understanding is that so far as regulations are concerned a DMU car is considered a locomotive, so it is subject to regulations that a non-powered coach is not, thus the tendency toward engine plus coach trains. Probably also means that EMU would also be considered as locomotives if in non-transit system use, but for the most part EMU's operate in areas where other issues are more significant than the extra inspections/maintenance issues raised by all units being powered.

By the way, the Shinkansen trains are not all axles powered. The cab cars on each end are not. Thus the 12 car trainsets used in Taiwan have 40 of their 48 axles powered. If you are going to have any non-powered cars, to have them on the ends is most logical, as the first few axles on a train will always have somewhat lower adhesion factors than the remainder due to dirt, rain, or whatever on the rail head.

 

[west point]

EMUs and loco hauled trains are at different ends of the operating costs. For steady runs with little speed changes locos work less expensive. EMUs really work better on routes with many speed changes and / or stations.

If the present Acelas operated on stretches with few slow downs then the present set up would work better. However an Acela that had multi cars with traction motors then the many speed ups needed would be quicker. How much time would be saved? Maybe 15 minutes BOS <> WAS?

There have been posts saying that EMUs do not work well with multi pans up. Have not seeen detailed report of such although some say 6 pans the most on the present NEC. Then there is also uncofirmed that FRA limits a power bus running across car tops? If so that limits possible multi cars providing traction.?

Then there is the matter of unsprung weight in relation of how the traction motors are mounted. Either on the trucks on in the car body?

 

[George Harris]

EMUs and loco hauled trains are at different ends of the operating costs. For steady runs with little speed changes locos work less expensive. EMUs really work better on routes with many speed changes and / or stations.
. . . .
Then there is the matter of unsprung weight in relation of how the traction motors are mounted. Either on the trucks on in the car body?

As to "different ends of the operating costs." This gets into how far apart are these ends? 10% difference, 50% difference or what? If the difference is not great, then it could be a non-issue.

When it comes to the unsprung mass issue, I really do not know how much difference this would make. My knowledge on this stuff basically starts at the top of rail and goes down, other than taking given information and calculating speed profiles. As to speed time acceleration issues, horsepower per ton is the magic number. The more axles you can spread this over, the easier it is to maximize this number without wheel spin. Also, the more axles you spread a required power per train over, the less power you need per traction motor, hence, smaller and lighter motors.

 

[Touchdowntom9]

As to "different ends of the operating costs." This gets into how far apart are these ends? 10% difference, 50% difference or what? If the difference is not great, then it could be a non-issue.

When it comes to the unsprung mass issue, I really do not know how much difference this would make. My knowledge on this stuff basically starts at the top of rail and goes down, other than taking given information and calculating speed profiles. As to speed time acceleration issues, horsepower per ton is the magic number. The more axles you can spread this over, the easier it is to maximize this number without wheel spin. Also, the more axles you spread a required power per train over, the less power you need per traction motor, hence, smaller and lighter motors.

In general are smaller motors more efficient than larger ones in terms of size and weight to horsepower? Or can you often double horsepower without doubling sizing and weight of a given engine?

 

[George Harris]

Also I thought many parts of the NEC used 155PS rail specifically to avoid being torn up by coal cars etc?

The 155PS rail is long gone. Think it was last rolled sometime in the 50's or 60's. The original NEC standard of the early 1970's was supposed to be 140RE, which is/was the 140PS renamed. Much of the line was already in 140 lb rail, by one name or the other. Don't think they are still using it, but have gone to either 136RE or 141RE. All of these (136, 140,141) have 6 inch bases, so they are essentially interchangeable so far as ties are concerned. The 155PS had a wider base, I think 6 3/4 inches, but I am not going to look it up right now.

 

[west point]

. Don't think they are still using it, but have gone to either 136RE or 141RE. All of these (136, 140,141) have 6 inch bases, so they are essentially interchangeable so far as ties are concerned.

Does that mean tie plates as well as ties?

 

[George Harris]

Does that mean tie plates as well as ties?

Yes. Actually, I meant to say tie plates in the first place, because on timber ties that is all that it would be, although if on concrete ties it would mean the ties themselves, since the rail fastener shoulders are embedded in the tie, itself.