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.
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.
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.
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 o
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.
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?
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.
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…
Gas-engined hydraulic rail puller/stretcher/expander. Portable, but…you try to movethat thing around in the cold and snow and then start the tempermental gas engine…The big castings and pump/engine pieces are almost always painted either dark green or lime green.
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