Breather Switch

A breather switch, expansion joint or adjustment switch is an intentional gap in lengths of railway tracks created to allow for expansion in long sections of otherwise unbroken rail. They are placed either between very long sections of continuous welded rail (CWR), at the transition between CWR and jointed track, and commonly in the vicinity of bridges and aqueducts where the infrastructure and track may expand at different rates.

Unlike a butt (flat) joint between two lengths of railway, each section is tapered diagonally, allow for a smooth transition and high-speeds across the gap.

Breather switches have two advantages over traditionally joined track. Firstly, they eliminate or significantly reduce the noise and minor wheel damage created when a train passes over the small gap between jointed rails, and secondly, where a section of CWR is particularly prone to expansion, these act as relief points to ensure that under extreme circumstances track does not warp out of shape or cause a sun kink.