Temperature efforts in the railroad

(Versión en español aquí: http://ingjoseguerrero.blogspot.mx/2013/11/esfuerzos-por-temperatura-en-la-via.html ).

The main element of the elastic railroad are Continuous Welded Rails or CWR.

(To see how they form these rails click here: http://ingjoseguerrero.blogspot.mx/2013/10/flash-butt-rail-welding-in-plant-2.html ).

Thanks to these long rails, the railroad is safer, comfortable and trains can travel faster.

However, while rails gets longer the deformations by varying its temperature increased, this causes severe damage to the railway, making impossible the moving of train on it.

As temperature increases the rails generate compressive stress causing them to expand and deform the railway:

(click to enlarge)

When the temperature decreases the tensile stresses cause rails to contract and break:

(click to enlarge)

When constructing elastic railroad, the rails should get to have their "equilibrium temperature". This temperature is different in each geographical region and should be studied case by case basis.

To ensure that the rail has its "equilibrium temperature" is performed a procedure called "rails efforts liberation", this basically involves applying heat to the rails by any method. In the following video we can see a machine called "Rail Heater" that is performing this procedure. (Thanks F. Drapeau consultants).