When a train passes over track, the rail has to do two things at the same time. It transfers vertical load down into the sleeper and ballast and also forces along its length — from temperature change, traction and braking. Those forces do not stop at the end of a rail. They must pass through whatever joins one rail length to the next. Every time two rails are joined, it creates an area where the behaviour of the track changes. These joins affect: How forces are transferred Ho

When two rails meet, the way they’re joined can shape the strength, longevity, and safety of an entire track section.

Most people assume a train should be perfectly balanced on a curve—tilted just right, riding equally on both rails. But that only works for one train, at one speed. On real railways, things aren’t that simple. Enter cant deficiency.