What is an expansion joint?

Expansion joint generally refers to the gap (seam) reserved to prevent thermal expansion and contraction, such as the original railway rail and the gap reserved between two rails. When the temperature is high in summer, the gap will be lengthened and narrowed due to the thermal expansion of the rail; When the temperature drops in winter, the rail will shrink and the gap will become larger. At present, all rails are welded rails, and the problem of thermal expansion and cold contraction of rails is solved by using the change of arc. Expansion joints are still used in stations or turnouts to deal with thermal expansion and cold contraction.