Continuous Automatic Warning System

Warning system for train drivers used in Ireland The Continuous Automatic Warning System (CAWS) is a form of cab signalling and train protection system used in Ireland to help train drivers observe and obey lineside signals. CAWS has been in use on Iarnród Éireann diesel trains since 1984. 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). Current equipment is supplied by SASIB, a division of Alstom. CAWS ADU on left, Acknowledge & Pre-departure test switches on right CAWS/ATP pick-up coil Principles of operation CAWS repeats the aspects shown by the lineside colour light signals on an aspect display unit (ADU) inside the driver's cab. The ADU continuously displays the aspect that was shown by the previous signal until updated about 350 metres before the next signal. The ADU then displays the aspect shown by that signal. A change of A