Electrical track circuits are isolated and defined from each other by the use of insulated rail joints (IRJs). The insulated joints can be of a mechanical or glued variety.

A mechanical IRJ is assembled on-site with a number of metal and insulating components.

A glued IRJ is where two short lengths of rail are joined in a factory by superior bonding techniques. The glued  joint, about 1-2 metres in length, is carried to the site and welded into place.