How do welded railroad rails compensate for thermals expansion and contraction?
Answer I looked into your question and spoke with a man who started his career at Pennsylvania RR, then became the chief engineer at NYC Subway, and SEPTA before assuming his current role as construction manager for a new light rail extension in a major midwestern city. He knows this stuff. He started by describing the early days of welded rail in the 1960’s when it was first used. Back then, each 1/4 mile section of welded rail had a buffer section between it and the next piece of track, which was changed out in winter and summer to accomodate longitudinal dimensional changes due to temperature variation. In the 1970s it was learned that if the connection of the rail to the tie plates/ties and the connection between the ties and the underlying ballast were equalized, thus eliminating stress risers along the length of the rail in both tangent (straight) and curved sections, the rail could be constrained in length and all expansion and contraction due to temperature variation could be a
