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effect of ice on traction?

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effect of ice on traction?
Posted by cleo3 on Friday, December 26, 2008 12:46 PM

I live in the Northwest.  I heard last week during our winter weather that Amtrak cancelled their trains for 2 or 3 days.  However, it seems to me that freight trains were still running.  Does snow and ice have a great negative effect on traction, or do the locomotives simply use sand continuously?  Is there something about passenger operations that causes freezing weather to have more effect on Amtrak's operations?

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Posted by henry6 on Friday, December 26, 2008 1:11 PM

The answers to your questions are yes and no.  A little ice on a rail can be overcome with sand but heavier ice conditions can cause slippage of a working locomotive and even sand tain't gonna help.  Using sand continuously is not wise for many reasons and there have been circumstances where it can eliminate circuit shunting if it accumulates (but that is so rare and with short or light trains or a set of light engines).  Amtrak operations, especially in the Northwest but anywhere outside Amtrak owned track (which is everywhere except the Northeast Corridor and a few other stretches in the Midwest and California) are at the mercey of the host railroad.  If the host road is messed up by snow, usually any tenant and any passenger train will be delayed over host road trains unless otherwise provided for.  Techinically, there does seem to  be problems of fine snow particles haveing more effects on today's diesels than in the past.  And of course, the loss of any power to signals and radio transmission towers, etc, will bring grief to any operation.

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Posted by Falcon48 on Friday, December 26, 2008 1:23 PM

nfan

I live in the Northwest.  I heard last week during our winter weather that Amtrak cancelled their trains for 2 or 3 days.  However, it seems to me that freight trains were still running.  Does snow and ice have a great negative effect on traction, or do the locomotives simply use sand continuously?  Is there something about passenger operations that causes freezing weather to have more effect on Amtrak's operations?

First of all, an important caveat.  I'm not a Class Ilocomotive engineer, so I'll necessarily defer to anyone who has this kind of experience.  That said, I don't believe that loss of "traction" in snow or ice conditions is a serious issue on conventional freight or passenger railroads.  The locomotives and rolling stock are heavy enough to crush their way through any ice or snow on the railhead, so the "traction" problem should be about the same as on wet rail. Snow or ice can, however cause other problems which delay or prevent rail operations.  Heavy snow accumulations (either by direct snowfall or drifting) can prevent any rail operations, not because of "traction" per se, but because the amount of snow is simply too much for the train to punch its way through without derailing or coming to other grief. Ice accumulations in flangeways (particularly at grade crossings) can lift the wheel flanges over the rail heads which, of course, can result in a derailment.  And ice can wreak all kinds of havoc on exposed wires such as signal lines and similar installations.  On electrified railroads, ice accumulations can also prevent contact with the overhead wire or third rail, which brings everything to a stop. 

With respect to your question about Amtrak, I'm not aware of anything that would directly make Amtak trains physically more vulnerable to ice, snow or freezing weather delays than freight trains, although it's conceivable that freezing weather could interfere with some of the "hotel" features of the passenger equipment (for example, by freezing water lines).  I suspect that the main reason Amtrak appears to be more affected has more to do with Amtrak's tight equipment supply than with ability to physically operate. If weather seriously delays Amtrak movements (even if the delays are no greater than freight delays), the equipment will not reach terminals in time to be turned for their next trips. Unless Amtrak has enough spare equipment available in the terminals to cover the outbound trips (and enough rested personnel to operate them), Amtrak will have to cancel or truncate the outbound movements. I imagine Amtrak has had enough experience with this kind of problem that they've learned to make the necessary schedule adjustments when they see it developing. That appears (to me, at least) to be the cause of many the cancellations and truncations Amtrak made in response to the recent spate of winter weather. The ones I saw appeared to affect originating trains, not trains that were already en route. 

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Posted by DennisHeld on Friday, December 26, 2008 4:32 PM
Another, more simple, reason that passenger trains are cancelled is that their 'freight' is unable to make it to the train. Why run a train with very little freight?
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Posted by Falcon48 on Friday, December 26, 2008 7:30 PM

henry6

The answers to your questions are yes and no.  A little ice on a rail can be overcome with sand but heavier ice conditions can cause slippage of a working locomotive and even sand tain't gonna help.  Using sand continuously is not wise for many reasons and there have been circumstances where it can eliminate circuit shunting if it accumulates (but that is so rare and with short or light trains or a set of light engines).  Amtrak operations, especially in the Northwest but anywhere outside Amtrak owned track (which is everywhere except the Northeast Corridor and a few other stretches in the Midwest and California) are at the mercey of the host railroad.  If the host road is messed up by snow, usually any tenant and any passenger train will be delayed over host road trains unless otherwise provided for.  Techinically, there does seem to  be problems of fine snow particles haveing more effects on today's diesels than in the past.  And of course, the loss of any power to signals and radio transmission towers, etc, will bring grief to any operation.

  You obviously have more direct knowledge of the effects of ice on traction than I do, so I defer.
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Posted by henry6 on Friday, December 26, 2008 9:44 PM

Falcon48

henry6

The answers to your questions are yes and no.  A little ice on a rail can be overcome with sand but heavier ice conditions can cause slippage of a working locomotive and even sand tain't gonna help.  Using sand continuously is not wise for many reasons and there have been circumstances where it can eliminate circuit shunting if it accumulates (but that is so rare and with short or light trains or a set of light engines).  Amtrak operations, especially in the Northwest but anywhere outside Amtrak owned track (which is everywhere except the Northeast Corridor and a few other stretches in the Midwest and California) are at the mercey of the host railroad.  If the host road is messed up by snow, usually any tenant and any passenger train will be delayed over host road trains unless otherwise provided for.  Techinically, there does seem to  be problems of fine snow particles haveing more effects on today's diesels than in the past.  And of course, the loss of any power to signals and radio transmission towers, etc, will bring grief to any operation.

  You obviously have more direct knowledge of the effects of ice on traction than I do, so I defer.

 

Do not defer, especially to me.  I know a little, very little, therefore am as dangerous as they come.  Most of what I say is what I have observed or experienced as a fan or from heresay from railroaders.  But that doesn't always make it true or correct.  You brought out some good points yourself.

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Posted by cleo3 on Friday, December 26, 2008 10:59 PM

Thanks for your answers!  What you've said makes sense.  I can see now why Amtrak would cancel trains whereas freight operations could absorb weather problems and still run some trains.  Thanks!  It does bring another related question to mind.  How much does wet rails affect traction?  Enough to need an extra locomotive pulling?  Like a car that can spin it's wheels on a wet road easily?  Or just a little loss of traction so that the train simply runs a little slower?  Are weather forcasts important to an engineer?

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Posted by BaltACD on Friday, December 26, 2008 11:16 PM

Actually, wet leaves have a bigger effect on traction....both acceleration and braking, than does ice and snow (within reason).  With ice from a ice storm, the lead wheel set, for the most part, will have impaired traction as it will be the wheel set that is the ice breaker, depending on the wheel slip control that the engine utilizes this may reduce power to either that wheel set or the entire truck.  Presuming the train is not loaded to it's maximum tonnage rating for the power it should be able to continue on it's way.

The bigger threat of ice and snow, is it's effects upon the signal and vendor supplied electrical systems, as well as railroad owned electrical systems. (pole lines).  While all signal control points are set up to have battery back-up when electrical power fails, batteries do discharge and then the control point no longer works.  While the normal response it to have personnel install generators, sometimes, under the severe weather conditions, the control point are not accessible.

When signal systems have failures, the fluidity of a railroad quickly slows down to restricted speed.  Under the situation of having failed signals systems on freight carriers that Amtrak uses, they will make a decision to cancel their service, since they don't have enough equipment to allow a train to be seriously delayed, without affecting the subsequent On Time origination of tomorrows train.

When Amtrak's Auto Train is seriously delayed, it can take a week or more to run it back On Time, unless at trip in each direction is cancelled.  There are only 2 sets of equipment that operate between Lorton, VA and Sanford, FL daily in each direction.  While there is enough equipment to add or subtract a couple of passenger cars or auto carriers depending upon level of traffic, there is not enough equipment to put a 3rd set in play if either of the scheduled sets are seriously late.

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Posted by zugmann on Saturday, December 27, 2008 12:17 AM

trolleys on the other hand...

.

http://www.youtube.com/watch?v=nawukWL3POY

  

The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.

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Posted by henry6 on Saturday, December 27, 2008 8:34 AM

BaltACD

Actually, wet leaves have a bigger effect on traction....both acceleration and braking, than does ice and snow (within reason).  to put a 3rd set in play if either of the scheduled sets are seriously late.

Metro North Railraod, New Jersey Transit Rail, and Souteast Pennsylvannia Transportation Authority all have special cars on special trains which spray rails to elimineate, or decrease the problem, of wet leaves on rail.  This is bad when trains must start, or stop, on grades.  Of course this is an Autumn problem.

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Posted by BaltACD on Saturday, December 27, 2008 9:41 AM

henry6

BaltACD

Actually, wet leaves have a bigger effect on traction....both acceleration and braking, than does ice and snow (within reason).  to put a 3rd set in play if either of the scheduled sets are seriously late.

Metro North Railraod, New Jersey Transit Rail, and Souteast Pennsylvannia Transportation Authority all have special cars on special trains which spray rails to elimineate, or decrease the problem, of wet leaves on rail.  This is bad when trains must start, or stop, on grades.  Of course this is an Autumn problem.

Baltimore's Light Rail system had virtually 1/2 their equipment out of service in in the shop account slid flat wheel from difficulties stopping on wet leaves this fall.  They had to reduce their service level account a lack of operating equipment.

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Posted by route_rock on Sunday, December 28, 2008 11:09 PM

  I have found the toughest part of ice on the rail and or snow to be starting a heavy train. But like posted mainline sand button in lead truck sanders on gets you more sand.I do the same trick when using the dynamics to get more bite for the wheels.

  Had a good snow and ice storm last night,13000 tons but did just fine.till the IC couldnt get us across and fred died then the htd so yeah it was a fun night.

Yes we are on time but this is yesterdays train

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Posted by Rodney Beck on Monday, December 29, 2008 10:00 AM

I have done both of the above frost on the rail is the unseen as far as wheel slip is concerened, nothing like going track speed and all of a sudden the engines are in wheel slip.

 

Rodney

 

 

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Posted by gngoatman88 on Monday, December 29, 2008 7:40 PM

Amtrak's cancelation of trains in the Northwest had nothing to do with traction, and no, there is not something about passenger operations that cause freezing weather to have more effect on Amtrak's operations than on freight in the manner in which I think you meant your question.

Passenger trains were canceled for a combination of reasons, the foremost being out of concern for the safety of the passengers.  The unusually cold weather and heavy snow had railroad operations all messed up in general.  There were frozen-up track switches, heavy snow fall, snow plow operations, threat of avalanches, etc. that just really clogged up the rail system or presented risks best avoided when it came to hauling passengers.  Freight is a different story.  There is a risk to crew members, but they are part of the railroad and risk is part of railroading.  Passengers are not part of the railroad and both Amtrak and the railroads simply didn't want to take chances when it came to passenger safety.

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Posted by monon99 on Tuesday, December 30, 2008 12:56 PM

As an active engineer in the midwest its been my experience that the locomotive model itself makes much of the difference. The old sd-40-2s were very well balanced and held the rail well, but the sd-50 with its stupid-series electronics is about as useless as a hand car when it starts to rain or snow,as it won,t hold the rail and you spend the whole trip with cramps in your hands from holding the sander on and adding a touch of independent to keep the wheel from spinning too fast. GE s in general are great pullers but the new steerable trucks after a while get more sloppy and the center axle hops under extreme loading(you know, 17000 tons 1.5 % and curvature with a 10% at the top  - my daily pleasure)at least I can watch the semaphores. Many of the latest sd-70s will actually lose traction at speed on the flatland at 60 per if it starts to rain and there's little you can do about it as they lock out the sanders because the computer knows so much more than me. Applying the independent will get you a nasty letter from the road foreman after a satellite download tells on you. Even on dry rail a wheel slip can end it all quickly. On the aforementioned hill I had a wheel slip from an sd-40 at 9 mph and it dropped me to 6mph, nearly stalled but it could have resulted in a knuckle with that much power and tension.

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Posted by Sunnyland on Thursday, January 1, 2009 2:49 PM

I agree with the post about Amtrak not wanting to take any risks with passengers.  A co-worker just returned from a Xmas trip to Chicago from St. Louis and the crew often had to get out and physically throw the switches because they were frozen.  With freights, the workers are employed by the RR but the passengers are not. Amtrak does not want to do something stupid and face a hefty lawsuit. Better to err on the side of caution.  Anyone who rides trains in the winter should be prepared for delays. This man and his family did, they had books and games to amuse the kids, he grew up in Philly where he rode a commuter train to school, so he knows all about trains and bad weather. 

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Posted by blue streak 1 on Thursday, January 1, 2009 3:07 PM

Monon99: I've had several engineers state the same thing about the SD-40s. Another said he felt it was too much HP on newer units on each axel and on several occasions he had road slug and felt most of the ice and wet rail problems disappeared. Of course it would probably cost too much to have slugs set up for 1 - 2% grades to use only in such conditions. What is you take on this?

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Posted by monon99 on Thursday, January 1, 2009 4:21 PM

 Well we keep coming back to trying to get one locomotive to do everything,an NYC gp-40 with little weight will rock on a piggyback but it won't pull a hill,slug sets are great for pulling and grip,but run out of breath closer to 30 mph. The latest engines from GE are super puller and do well at speed - if they would just load quicker. CSX has done a marvelous job with the optimal weight issue(as in trains article) the "heavy 44's" pull like monsters but all the new stuff falls down when the electrical monitors fail. CSX recently started to add hi-pressure air jets to dry the rail ahead of the sanders ala Madison hill sd-7s and I can verify that it seems to work superbly - just wish they all had it. You go from singin' in the rain to marching right up the hill - no problem. I had one of the first ac-6000s on a grian train by itself when we got to the second cut of 10 cars to double out it wouldn't move - all 6 axles were in rotten corn mash slime and all 6 axles self-cutout due to wheel slip! That was a long night.

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Posted by Deggesty on Thursday, January 1, 2009 5:05 PM

zugmann

trolleys on the other hand...

.

http://www.youtube.com/watch?v=nawukWL3POY

Ah, yes. You would get the same effect with trackless trolleys, especially since both sides of the circuit depend upon the contact of a trolley with the overhead wire. An ice storm hit Atlanta New Year's night of 1961. I arrived in Atlanta from Jesup the next morning, and rode a trackless trolley out to Decatur. The lights inside were bright when we were standing still, but grew dim as we accelerated, not just because the motor was drawing power, but also because the contact with the wire was not as firm when we were moving as it was when we were standing still. Of course, there was arcing and sparking, but we did keep moving.

Another hindrance to traction: oil on the rail. Back in '64, I made a round trip on the Carolina Special from Asheville to Hayne (just outside Spartanburg; the conductor advised me not to go on in to Spartanburg, lest I miss the westbound train. Going back, we had plenty of power until we reached the foot of Saluda Hill, and met the weed spraying train, which had let some oil drift onto the rails. For some reason, our sanders were not working well, so we lost about an hour on the hill.

Johnny

Johnny

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Posted by JayPotter on Thursday, January 1, 2009 6:55 PM

monon99
CSX recently started to add hi-pressure air jets to dry the rail ahead of the sanders ala Madison hill sd-7s and I can verify that it seems to work superbly - just wish they all had it. You go from singin' in the rain to marching right up the hill - no problem.

The "high tractive effort" AC4400CWs (class CW44AH) and ES44ACs (class ES44AH) have RailCleaners; and they're also installed on standard-weight AC4400CWs when they are upgraded to CW44AHs.

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Posted by monon99 on Saturday, January 3, 2009 8:07 PM

Oil is fun!

I once was switching out a facility that added the "additives" to make the little bottles of expensive oil and hadn't been in there before,it was a bit steep down to the siding and the coupling was a bit rough(well they always told me that there wern't eggs on the coupler) anyway somebody hadn't thought to close the hatches before we coupled in - insert conductor joke here - and the impact sent geysers of oil skyward from about 10 tanks one after the other! When we tryed to pull the cars nothing happened,we just sat and spun. I had to uncouple and lay down sand making several passes before we could get out.

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