Assuring the functional safety of a complex railway signalling interface

This paper describes the methodology and processes used to assure the functional safety of a complex railway signalling interface between a new Transmission/Communication Based Train Control (TBTC or CBTC) system and an existing computer-based signalling system on the London Underground Limited (LUL) infrastructure. The approach applied for verifying and validating the system requirements; resembles that of a typical project lifecycle model.