How are communications or signals failures handled?
In case of signalling equipment or block equipment failure (e.g., power failure, floods), if communications can be established between adjacent stations (by telephone on the public network or control telephones of the railway network, or in the past, by telegraph or bell code), paper line clear tickets may be issued to trains to proceed. Such paper authority is given along with issue of private numbers by station masters to establish proper authorization, authentication, non-repudiation of the action. Paper or verbal authority to proceed (with issue of private numbers) can also be given by section controllers if communications have broken down between adjacent stations. If there is a total breakdown of communications, the station master of a station can still issue a paper authority to proceed to the first scheduled train departing a station, subject to a restriction to run at or under 15km/h and a requirement to sound the horn or whistle freely to alert any possible oncoming train.
