New York City Transit (NYCT) is modernizing the signaling system in its subway by installing CBTC and replacing relay-based interlockings with computerized, solid state interlockings (SSIs). Computerized SSI software demands new and improved safety verification, and long-term also reduced cost and time for performing safety verification.
For this purpose, NYCT today requires formal verification of SSI software using Prover iLock Verifier. The safety verification is performed as part of the independent safety assessment (ISA), and checks that NYCT’s generic safety principles are met by the SSI software.
[This verification process is applied for multiple SSI vendors.]