The analysis of transport network reliability under a natural disaster warning (eg impending tsunami) is a complex task, in part due to the uncertainty of the time of the event-occurrence at different locations. Different magnitudes and epicentres of earthquakes will cause tsunami waves to have different arrival times and wave heights in different locations. In this study, the Southern coastal railway line in Sri Lanka, which is in part single and in part double track, is analysed to plan for the operation of trains under a tsunami warning. The confusion and concern that will prevail among passengers is considered. The poor communication and signal system in place is considered. Planning guidelines are proposed to improve communications, select ‘safe’stations under various tsunami scenarios, as well as select ‘evacuation’stations. A simple procedure for assigning trains to safe or evacuation stations is proposed.