System Safety Process and Design Process in Road Tunnel Control Systems

Safe by design, is the aim of all conscientious design houses involved in safety critical designs. Road tunnel control systems are regarded as safety critical because a tunnel is the most hazardous environment to road users and those involved with the maintenance of road structures. Road tunnel systems\´ interfaces with classical systems such as COBS and new control elements such as TSS make it particularly difficult to analyse for safety requirements. Good design ethos although necessary for a safety critical system is not sufficient on its own. System safety is a process that has to be enshrined into the design process in order to deliver a "safe design". This paper highlights a relationship between the safety activities and the design process for a tunnel control system that helps achieve the aim of safe by design.