Indian Railways, keeping in pace with the advanced railways of the world, has adopted welded rails in the last few decades. The development of the welded rail has been necessitated due to economic considerations coupled with the technical advantages of a welded track over a fish-plated track. Rails were initially welded into panels of three, five, and ten rails. The development of these rail panels, called short welded panels (SWP) or short welded rails (SWR), was the first stage in the development of welded rails in the country. In the due course of time, there were considerable advancements in track technology, and a new concept of 'locking up of stresses' in the rail, which thereby resisted any changes in the length of the rail, was developed. Accordingly, long welded rails of varying lengths of up to 1 km were laid to eliminate rail joints and make the most of all the advantages that welding offers.
The concept of continuous welded rails is now developing rapidly and welded rails are being laid continuously so as to get the full advantage of a jointless track.