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First of all, I'm interested in train track only, not the rolling stock.

How are tracks built to cope with really cold weather? An example might be some place in Canada or Siberia. Ice would accumulate all the time, changing the shape of the rail.

How does the ballast or foundation cope with the thawing tundra in summer? What about the really nasty stuff like blizzards dumping snow over the track, or sleet, or freezing rain?

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    $\begingroup$ you worry too much about ice and snow and not enough about the metal shrinking and expanding with temperature changes. Sleet is by no means the "really nasty stuff" if you're running a railway. $\endgroup$ Feb 21 '16 at 16:34
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    $\begingroup$ @KateGregory I already know how to handle thermal expansion/contraction. Use breather switches (expansion joints). What I don't know is how to handle the rail changing shape to due to ice buildup. That ice could come from rain, sleet, or really any precipitation. Water's volume expands 9% when freezing, and if it gets in the nooks of a railroad, it can crack it. $\endgroup$
    – DrZ214
    Feb 21 '16 at 23:09
  • $\begingroup$ Were you asking about the brittle transition temperature of the steel ? $\endgroup$ May 8 '18 at 13:09
  • $\begingroup$ @blacksmith37 Not really. If I'm not mistaken, there are different alloys of steel to stay non-brittle at different temp ranges. What I was really worried about was "frost heave". I just didn't know that term at the time. Another concern was how often does a snow plow need to run the track and how long that takes. $\endgroup$
    – DrZ214
    May 8 '18 at 15:04
  • $\begingroup$ Rail steel is brittle at those temperatures. $\endgroup$ May 9 '18 at 19:47
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Precipitation

Snow

Snow can be a problem for running trains, but it really doesn't affect the rail/ballast. Just like on highways, the snow needs to be moved away, but it doesn't have many other effects.

Trains are used to plow through small amounts (Wikipedia):

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and large amounts (Wikipedia):

enter image description here

Ice

Ice could cause more of an issue due to adding thickness to the rails. This is mostly handled by making the trains travel slower. The weight of the wheels on the rail is enough to crush through any ice that has accumulated, i.e. trains are really heavy. As long as the train doesn't move too fast, it isn't in danger of derailing.

Track Components

Switches

Switches need to move in order to operate. Ice and snow accumulations can cause issues if they keep the components from moving. It is for this reason that most switches have switch heaters installed. These are gas powered heaters that blow hot air in the appropriate locations to melt any snow or ice.

Rail

Like mentioned above, the rails aren't really affected by ice or snow. They are just chunks of metal. The biggest issue that rails face is the cold.

Rails are restrained by rail anchors from expanding and contracting due to temperature changes. If the weather gets cold enough, the rail won't be able to contract enough and the stress will be so great that the rail will break. This isn't as much of an issue as you might think though. Many sections of railroad use the individual rails to transmit signal controls. They are set up to failsafe, so that a broken rail is the same as a broken connection. This will show a stop signal.

Ties

Ties are hunks of wood. They aren't really affected.

Ballast and subgrade

As you mentioned, freeze and thaw will cause issues due to volume changes. These effects can be foreseen and dealt with.

The ballast section should be designed to drain water. If there is no water, there is less chance of volume changes. The same can be said for the subgrade. Drainage is key.

Apart from a good design, freezing and thawing happens every year. It is very predictable. During the time periods where these effects are likely to cause issues, the track can be inspected regularly to keep it in geometric tolerance.

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  • $\begingroup$ For the rail, what about ice on the side of the rail? Doesnt this change the thickness and thus affect how the wheels run? $\endgroup$
    – DrZ214
    Feb 21 '16 at 23:12
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    $\begingroup$ @DrZ214 It breaks off. Trains weigh a lot. It's all about going slow if there is a lot of ice (think first train of the commute for metros). After that, ice shouldn't be an issue. $\endgroup$
    – hazzey
    Feb 21 '16 at 23:29
  • $\begingroup$ Both Ice and snow can be real problem for trains trying to get traction in the right / wrong conditions. I've been stuck on trains unable to run in both conditions but all it took was one train to get through to clear the tracks for following trains. $\endgroup$
    – Ian Turner
    May 8 '18 at 15:41

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