 All NIR trains operating cross-border must also be fitted with CAWS.Coded track circuits, which form the basis of the system (see below), are installed on all Dublin Suburban and Intercity routes to Cork, Limerick, and Athlone and as far as the border on the Belfast line.This system is of American origin, being originally supplied by US&S, then a division of Westinghouse Air Brake Company (WABCO).