They are calling for -20 this week in the midwest. We know about heat kinks but what about steel getting more brittle under cold temputures? I am worried about wheels and rails cracking and breaking under extreme cold.
CN has put out a publication advising customers, investors and government people what their plan is for the 2019-2020 winter operations. It discusses the effect of temperature on rail, equipment and operations at various temperature ranges and advises of their operational procedures. Go to
https://www.cn.ca/en/your-industry/customer-reports/winter-plan/ and view or download plan for winter 2019-2020
PS: you will have to convert from centigrade to farenheit. Note: -29 C = -20 F,-40 C = -40 F.
Track forces will be out looking for pull aparts and blind joints in cold weather conditions just like they do in summer with sun kinks. In signal territory, you get some warning of a pull-apart in the cold.
The biggest headache in cold weather remains trainline air followed by anything with a lubricated friction component seizing up...
Firesnake and Green Monster season approaches.
Rail, especially continuous welded rail, will shrink with the cold temperatures. It is normally joined in warm weather. The shrinkage will reduce radii of curves and may produce strains that break rail joints. Normally, there are bulletins out for low temps and inspectors and trains will watch for breaks.
Not so much an extreme cold issue, but snow can build up between the wheels and the brake shoes, resulting in - no brakes.
In wet snow weather, astute engineers will make an application from time to time simply to warm things up a bit. This is especially true when a known call for brakes is upcoming.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
Right: Extreme cold will also create or expose gaps in air brake fittings meaning that keeping pressure will be difficult (requiring shorter trains). The same brittleness in steel rails extends to wheelsets. And, engines not kept warm or in a place where they can be warmed are in danger of not restarting or functioning properly due to any combination of oil solidfying, moisture condensing from the air and freezing where it shouldn't, radiator damage, and dead locomotive batteries.
Actual railroaders could comment if they've found critters sheltering in the equipment, just like the squirrels or chipmunks used to get into the air filter of my dad's Comet.
Steve SweeneyDigital Editor, Hobby
Before the advent of WILD (Wheel Impact Load Detector) detectors being installed, and there reports acted upon, there were a lot of seriously flat wheels operating all over the country - the edge of the flat, pounding into the ball of the rail in extremely cold conditions acts like cold chisel creating a 'nick' on the rail that can grow into a fracture of the rail with the vertical stresses that happen as wheels pass over the point, flex it with each wheel set the moves.
The Class 1's use of WILD detectors has greatly reduced the number of cars operating with flat wheels.
Never too old to have a happy childhood!
Cold is almost a worse problem than heat, for CWR much more so. The determination of a correct 'neutral temperature' for engineering welded track is weighted toward individual climate (or microclimate) to reduce the number of days particular watch and special attention needs to be paid to temperature excursions 'outside' the range, and on some systems that can 'afford' it (I believe the 'T' in Boston is a recent example) operations will be cut back or suspended in extreme cold snaps in significant part to avoid the kinds of cold-weather problems Balt and others have mentioned.
In severe hot weather it is possible to remove small amounts of rail 'anywhere' to relieve the longitudinal pressure. Contraction requires insertion of new rail, which may not solve contraction stresses even a comparatively short distance away. While the lighted-rope method of end-loading a rail for field-welding still works, the arrangements to put in a piece of new rail in very cold conditions are much more involved and painful, and I'd expect a temporary cutout and bolted 'temporary' insertion to be more common.
The wheel damage problem is not just related to increasing number of flats from 'skidding gone bad'. I have seen a couple of discussions that brittle failure producing broken wheels is greatly increased in very cold environmental temperatures; while of course this would be greatly facilitated by stress raisers initiated by flatting, it might also originate from other less evident damage or unseen propagating flaws.
The interesting thing about Tree's problem is that, once there is significant 'pack' in between wheel and shoe and a brake application mechanically compresses this to ice, the 'no braking' period can be considerably prolonged even in conditions that are not 'bitterly' cold. The polished wheel tread acts like the runner of an ice skate to melt just a small layer of water, which in the confined contact space is an excellent gliding lubricant. Part of this film will be carried out of the space by the wheel, but will probably refreeze on the tread rather than evaporating, causing potential issues at the wheel/rail interface lower down. I believe I have also read instances where, after a stop with shoes in this condition has been made, the extended shoes have frozen to the wheels beyond the capability of the return springs in the air brake to overcome, so on release the train must exert enough additional tractive effort to debond all the ice films in shear...
I believe the 'loose air-brake connections' problem is endemic in a considerable amount of interchange traffic, and one of the reasons locomotive air compressors are designed with considerable 'excess volumetric capacity' is to pump up trainlines with a large number of effective leaks, the way someone would have to pour faster to fill a flowerpot tipped to sprinkle. I remember a story decades ago now in Trains about a solid trainload (pun not intended then, but intended now!) of beets in far-from new cars, where the duty crew sat for a couple of hours pumping but couldn't get pressure to the point of release. Presumably one reason yards would provide air was to accelerate this process without a lot of lost time and locomotive-compressor wear. In steam days the compressor use would have entailed considerable consumption both of fuel and water, and involved the potential boiler problems from sustained operation on blower.
Someone with metal knowledge. Do rapid temperature changes cause more problems than gradual changes ?
Yes. That's why, in the aircraft industry, zillions have been spent perfecting the metallurgy for compressor blades in jet engines. They are forced to go from Alaska/Edmonton/Winnipeg/Vladivostok -40C/-40F at start to 1300C (or whatever it is) inside of a couple of seconds.
That sounds more like the turbine blades, compressor outlet is more likely 300C at max. This also true of aircooled piston engines, particularly with aircraft engines where a sudden cut in power can cause a "shock cooling".
The problems mainly occur when cooling or heating happens so rapidly that a large temperature gradient forms in the material leading to internal stresses due to thermally induced expansion or contraction (particularly bad with brittle materials). This can be limited by using materials with a low coefficient of thermal expansion (e.g. true "Pyrex" glass).
Turbine blades of course have maximum inlet temperatures. Allison turboprop engines had a turbine inlet temp max about 940 C. later jet engines had a higher inlet temp so thermo couples started being move to locations farther down stream of the turbine chain. Most jet engines have 4 and sometimes up to 6 turbine stages, Many early engines such as the JT8 had exhaust gas temp guages. Compressor stages usually run 13 - 15 not enough to have light offs. Spaark plugs required.
Usually only when in test cells will engines have guages inserted for tests of all stages.
blue streak 1Do rapid temperature changes cause more problems than gradual changes?
Yes, but the temperature gradient change in any kind of weather change is orders of magnitude slower than those that produce metallurgical shock.
The effects are more pronounced when there is external shock under what are essentially cold-soak conditions, and furthermore the effect of contraction can produce cumulative stress that will propagate as a kind of 'recoil' shock through the denser cold metal and can cause brittle failure if the metal has gone below the brittle transition (see the discussion we had recently on Liberty-ship weld failure, the Titanic's rivets, and associated subjects).
To me, the likeliest 'rapid-onset' issue would be if you have a rolled car wheel at low temperature and substantially heat its rim with sustained braking. Even so, the particular composition and fabrication of the wheels are meant to help spread some of the differential stress so as not to induce cracking or failure -- that's one of the points of modern wheel fabrication via older chilled-tread (not related to cold environment, but to metallurgical methods of hardening the tread area without making the main part of the wheel more brittle) designs.
There's a long history in the railroad industry of ignorance of the effects of extreme climate until 'too late' -- the whole early history of rubber car springs as recounted by John White being an example.
[quote user="mudchicken" Firesnake and Green Monster season approaches.[quote]
Firesnake I understand, but what is a Green Monster?
Steve Sweeney Actual railroaders could comment if they've found critters sheltering in the equipment, just like the squirrels or chipmunks used to get into the air filter of my dad's Comet.
It happens:
https://www.cbc.ca/news/canada/edmonton/engineer-conductor-rescue-miracle-cat-that-hitched-cold-train-ride-in-alberta-1.3892471
Greetings from Alberta
-an Articulate Malcontent
mvlandswFiresnake I understand, but what is a Green Monster?
Suspect it is a turbojet switch snowblower, named for Art Arfons' LSR jet car.
All the ones I have seen were yellow, but UP and maybe other roads painted their MofW equipment green.
Steve SweeneyActual railroaders could comment if they've found critters sheltering in the equipment, just like the squirrels or chipmunks used to get into the air filter of my dad's Comet.
Can't say as I've seen that, perhaps aside from some little critters who have left evidence. Aside from really cold nights like the last couple, we usually leave our locos on Hot Starts (block heaters), but aside from lots of air leaking in (last night's runs were a bit cool in the drafty cab), there's not a lot of places to sneak in anyhow.
More worried about the wood goats (deer) who can't decide whether to run left or right...
[quote user="mvlandsw"]
[quote user="mudchicken" Firesnake and Green Monster season approaches.
Overmod . . . I remember a story decades ago now in Trains about a solid trainload (pun not intended then, but intended now!) of beets in far-from new cars, where the duty crew sat for a couple of hours pumping but couldn't get pressure to the point of release. . . .
http://trc.trains.com/Train%20Magazine%20Index.aspx?articleId=66868&view=ViewIssue&issueId=5985
The crew was astounded that they had been called to move dead, frozen low-priority freight on such a cold, miserable night. As I recall after like 7 hours they went uptown to eat. It never did attain the required pressure during their tour of duty, or at least it never left the yard.
- PDN.
mudchicken . . . Track forces will be out looking for pull aparts and blind joints in cold weather conditions . . .
Paul_D_North_Jr Overmod . . . I remember a story decades ago now in Trains about a solid trainload (pun not intended then, but intended now!) of beets in far-from new cars, where the duty crew sat for a couple of hours pumping but couldn't get pressure to the point of release. . . . It was this article in the February 1973 issue: Battling blizzards on the Big G working as a brakeman in the winter by Patrick, Howard S. brakeman GN snow winter http://trc.trains.com/Train%20Magazine%20Index.aspx?articleId=66868&view=ViewIssue&issueId=5985 The crew was astounded that they had been called to move dead, frozen low-priority freight on such a cold, miserable night. As I recall after like 7 hours they went uptown to eat. It never did attain the required pressure during their tour of duty, or at least it never left the yard. - PDN.
It was this article in the February 1973 issue:
Crews spending their entire tour of duty pumping air, and never being able to turn a wheel was a 'relatively' common back in the days of steam and early generation diesels - their air pumps were were not equipped with 'air driers' and pumped a lot of water, squeezed out of the air they were compressing through the train line. Crews would routinely add alcohol to the compressor inlet to have the alcohol act as 'anti-freeze..
Today's locomotives had air drivers and the use of alcohol is prohibited.
In very cold weather, snow and ice can build up on the tracks blocking points, the equipment that allows trains to move between tracks. To de-ice the ice on road, usually they will put salt. Good question that raised. Now I'm thinking is it possible for ue to put salt on the rail to melt the ice?
sciloverIn very cold weather, snow and ice can build up on the tracks blocking points, the equipment that allows trains to move between tracks. To de-ice the ice on road, usually they will put salt. Good question that raised. Now I'm thinking is it possible for ue to put salt on the rail to melt the ice?
Possible - not practical or encouraged. Salt enhances the creation of rust on metal surfaces - switch points slide on metal surfaces that normally have dry graphite applied as the lubrication - it is desired to keep the switch points and the surfaces they move upon with dry lubricants. Wet lubricants (oil & grease) attract dirt and dust and end up being abrasives not lubricants.
At control points that are operated from remote location, various forms of 'switch heaters' are employeed to keep the switches operable. The form of the heaters raing from 'smudge pots', LPG fired heaters, electric heaters, cold air blowers and any other device thought to be able to keep the points free of snow and ice.
When these means fail - MofW personnel with brooms and ice chippers come to the rescue.
scilover... is it possible to put salt on the rail to melt the ice?
MC and diningcar are two participants who will have specific discussions about what works and doesn't work in snow and ice clearance. But before we go there, a few key distinctions need to be made.
Roads are salted because salt water freezes to (dangerous) ice at a lower temperature. Ice on roads is only severely dangerous to the extent pressure or friction can form a thin layer of liquid on the ice surface, the principle on which skates work; ice below about 23 degrees does not show this effect.
The situation of ice on the contact patch of the railhead is more complicated, in part because the thermal mass of the rail will near-instantly chill a thin film of water, but the severe pressure at the contact patch will liquefy ice on the railhead and compress it to a thin film. Using salt here, say as an additive to traction sand, would not affect the essential slip problem 'much more than sand alone' -- and salt is hygroscopic, corrosive, and likely would lead to caking problems, one of the LAST things you'd intentionally provide in any traction-sanding system.
Meanwhile, a second serious problem is that of flangeways, for example at crossings. Here the ice buildup is to an extent that salting with NaCl won't reach, and the practical amount of flange lifting to risk derailment is only on the order of ¾" or so. Therefore the preferred method is to use a flanger periodically to mechanically, and effectively, remove dense buildup of ice or snow (or ponding that proceeds to icing solid).
The chief danger at switchpoints (as I understand it) is not so much that the linkage will freeze and make the switch difficult to throw as that motion of the points will pack snow and ice to keep them from fully locating. This makes for a number of dangerous situations and no good ones. The bad news here is that salt won't even begin to alleviate the mechanical blockage, even if you could somehow get it to stay in the vertical space where, say, the point contacts the stock rail.
Over the years some very clever people have had nifty ideas about melting the snow, one of which I believe actually involved UP8444 for a while: the idea being to use the Power of Steam (which has an enormous heat of condensation) to both melt and blow away the offending ice/compressed snow. This worked dramatically well until, alas, the steam was turned off, at which point the water refroze as above in a thin and mechanically strong layer that was 'a cure worse than the disease'. As I recall, in the wake of WWII there was the idea you could mobilize a switch heater in the form of a flamethrower (which to me indicated there were MOW people who didn't exactly recognize how switch heaters did their work) and then the idea that really, really hot gas-turbine exhaust (from cheap obsolescent aircraft turbojets) would give you directable heat. The idea actually worked after a fashion in the combination of heat and blast... but then came the problem of moving ballast at ballistic velocities...
One other reason not to use salt on rails is that salt can play havoc with track circuits.
UP and, presumably, many other roads would reduce originating train length ahead of predicted low temperatures - varying according to predicted lows. Trains enroute would generally keep going until they might experience air problems and often reduced in length enroute when necessary. I suspect DPU operations may have improved air flow in cold temperatures. Back in PRR/PC days used to commonly have to pump alcohol through a train that stopped to set out or pick up, for example, to gets its brakes released. Often the decision is made to eliminate breaking a train line below certain temperatures. UP had its protocol for operations at low temperature ranges prescribing length and maximum speed. >
Broken rails have been a major bugaboo of winter operations, often arising en masse with the first real cold snap of a season and a common task for maintenance of way crews. Often a broken rail is passable, whereby a qualified employee on the ground can roll a train over the break at reduced speed. If the break is to such extent that it is impassable, you are done dealin' until MofW can get on the scene, place joint bars or patch the rail. Real fun when switches are drifted in and you cannot route other trains around the break (call 1-800-dog-ctch). Flat wheels could and will tear up a piece of railroad in extreme cold and fortunately detectors make this an unusual occurrence these days, as mentioned above by BaltACD. >
In hot weather where expansion can be a problem, the proverbial sun kink, MofW is on heightened alert, hi-railing. The real danger here is that track circuit continuity is not affected as with a broken rail in most cases. Thus rules prescribe the method of train braking so as to minimize stress on the track structure during high temperatures for a given district, as well as maximum speed for various tonnages. >
SD70Dude Steve Sweeney Actual railroaders could comment if they've found critters sheltering in the equipment, just like the squirrels or chipmunks used to get into the air filter of my dad's Comet. It happens: https://www.cbc.ca/news/canada/edmonton/engineer-conductor-rescue-miracle-cat-that-hitched-cold-train-ride-in-alberta-1.3892471
Great story about the cat! I'm having trouble picturing where he was, though. Can someone shed some light on this?
Lithonia Operator SD70Dude Steve Sweeney Actual railroaders could comment if they've found critters sheltering in the equipment, just like the squirrels or chipmunks used to get into the air filter of my dad's Comet. It happens: https://www.cbc.ca/news/canada/edmonton/engineer-conductor-rescue-miracle-cat-that-hitched-cold-train-ride-in-alberta-1.3892471 Great story about the cat! I'm having trouble picturing where he was, though. Can someone shed some light on this?
It's been a while, but I seem to recall looking up that train at the time, and the second (dead) unit was a EMD SD75I.
I suspect the cat had been hiding on top of the fuel tank, in behind the air reservoir. As this is directly underneath the engine that area would still be fairly warm and sheltered in the winter. There may also be holes in the frame large enough for a cat to climb through into the engine compartment.
PennsyBoomer In hot weather where expansion can be a problem, the proverbial sun kink, MofW is on heightened alert, hi-railing. The real danger here is that track circuit continuity is not affected as with a broken rail in most cases. Thus rules prescribe the method of train braking so as to minimize stress on the track structure during high temperatures for a given district, as well as maximum speed for various tonnages. >
At what point, if any, would ambient air temperature be considered too hot to continue operations?
Has a U.S. railroad ever shut down operations because it was too hot?
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