Case study: Traffic Alert and Collision-Avoidance System

when they were writing the specification, but that was late in the process. RATP would have liked direct simulation of the specification. UK government groups. GEC Alsthom has used B in two subsequent applica­ tions: a transportation system in Calcutta, India, and a safety net to protect against driver failure on all the electrified lines operated by the French national railways authority. • REFERENCES To improve an industry-government working group's capability to review this system, which alerts and advises pilots in the event of an impending collision, formal specifications of two major subsystems were developed using a formal, graphical notation.