why no gap is left for expansion in welded rails of indian railway?

Question

how the expansion is catererd due to temperature raise on rails

Answer 1

It is the same in the US with "ribbon rail", a.k.a. CWR (Continuous welded rail).

Standard 78' lengths of rail are welded together and loaded onto a ribbon rail train in 1320' sections. When the rail is laid, these sections of rail are welded together.

Expansion is a problem. The rail is held in place by conventional tie plates and spikes, but have an additional device applied called a "creeper". This is kind of shaped like a candy cane and when installed prevent the rail from moving along its longitudinal axis. In addition, the rail is engineered to accept these stresses.

Even so, in the US, when temperatures are very hot, trains are ordered to operate at reduced speed via what is commonly called a "heat order". This is because there is a propensity of the rail to want to buckle under the sun and has caused many derailments in the past.

The flip side of the coin is in deep winter in mountainous areas where there is snow on the ground and extremely cold air temperature. In this instance the rail contracts and will create a "pull apart", with the rail breaking. This happens almost nightly and is therefore very common, but is a safer consequence, as when the rail separates it will knock down the signals so the approaching train will be running at "restricted speed", which includes a proviso for "looking out for broken rail".

So, the technology came with some built in drawbacks, but overall there is far less maintenance needed where ribbon rail is used.

Answer 2

To my hearsay iwas told instead of the traditional joint plates in between each rail which was proved complex for maintainenance,four to five rails are welded till the allowance of expansion due to heat is taken care of which is proved sucessful & economic also is the methodology followed now.

thanks
als