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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Snow drifts can cover tracks, moisture can freeze in airbrake hoses and frigid temperatures can affect steel rails.
Extreme cold can cause rails to split or crack. To make sure these defects don't pose safety hazards or disrupt operations, railroads perform ongoing track inspections.
Tracks are affected by extreme cold in two ways. In some cases the tracks experience what's called “pull-aparts.” This kind of rail defect occurs when two rails separate at their connection. The extreme cold shrinks the metal and the rails literally pull apart from each other, Metra said in a recent Instagram post.
Emissions: The rail network, for both passengers and freight, produces lower GHG emissions than roadway and air transportation, which means that shifting trips from road and air to rail in markets where it makes sense can reduce overall transportation emissions.
Because rails are made from steel, they expand as they get hotter, and can start to curve this is known as 'buckling'. Most of the network can operate when track temperatures heat up to 46°C – roughly equivalent to air temperature of around 30°C – but rails have been recorded at temperatures as high as 51°C.
You will often find propane heaters that will keep the switches clear of snow and ice on mainline tracks in Canada and the Northern US. The tracks otherwise are not heated and in severe cold have significant speed reductions due to possible brittleness and contrction.
One instance is where the railway track is at a slightly higher level than the road approaches on either side. A long vehicle such a s a low loader can become grounded on the “hump”. Another situation is where, at a level crossing, a driver mistakenly leaves the road and turns onto the tracks.
CapMetro said anytime a track's temperature reaches 135 degrees or higher, the trains have to slow down for safety purposes and to prevent serious damage to the tracks. Extended periods of extreme heat can cause tracks to bend, warp or reshape entirely, otherwise known as a sun kink.
Excessive rain can destabilize terrain, resulting in dirt or rocks on the tracks. Localized landslides can cause derailments. (While technology like a so-called slide fence, which signals trains to stop if significant debris hits the tracks, helps, it cannot prevent the damage.)
The critical rail temperature is the temperature of CWR at which measures to protect traffic must be taken. It depends on the actual stress-free temperature, resistance to lateral movement offered by the ballast (ballast condition), track curvature and sleeper spacing.
If you can't walk or cycle, then public transport is usually your best option. Trains are particularly low-carbon ways to travel. Taking a train instead of a car for medium-length distances would cut your emissions by around 80%. Using a train instead of a domestic flight would reduce your emissions by around 86%.
If we take an overall view of the transport sector, 71% of transportation related carbon emissions come from road users, whereas only 1.8% of emissions stem from rail travel. So in absolute terms, trains are responsible for a lot less emissions than cars.