The Signalling Unit operates around the world designing and building rail and subway signalling systems and components through four operating companies: Ansaldo STS SpA with sites in Genoa, Naples, Turin and Tito Scalo; Ansaldo STS USA with sites in Pittsburgh, PA and Batesburg, SC; Ansaldo STS France, which has sites in Paris and Riom; and Ansaldo STS Australia which has its offi ce in Brisbane, Queensland.

The Group also owns smaller operating companies in Germany, Kazakhstan, Finland, Sweden, Ireland, the UK, Spain, China, India, Malaysia, South Africa, Botswana and Brazil as well as several permanent establishments and cooperation agreements including South Korea, Libya and Turkey. 
 

The main projects in which the Unit participates or has participated, wholly or partly responsible for completion, include: 
 

the installation of computer-based interlocking systems in Italian railway stations (Rome Termini, Pisa, Venice Mestre and Milan Rogoredo) and outside Italy in Manchester South and the Sandbach-Wilmslow junctions (UK);
 

signalling systems supplied to the automated mass transit systems in Copenhagen, Brescia and the subways of New York, Los Angeles Green Line, Shanghai Line 2 and Tianjin-Binhai, PRC;
 

electro-rail systems for Metro line 3 in Milan and complete signalling installations and systems on the railway lines of Rawang Ipoh, Malaysia, and Hammersley Iron, Australia;
 

signalling systems for high-speed trains in France (TGV), the Spanish Madrid-Lerida line, the South Korean Seoul-Taegu line, and the Chinese Qinhuangdao-Shenyang line, while in Italy the Group is involved in the high-speed trains programme (Milan-Bologna and Turin-Novara sections) supplying signalling systems through the Saturno consortium;
 

supplying the signalling systems, telecommunications, security and power supply for EUR 541 million for the Ras Ajdir-Sirt (circa 650km) and Al Hishah-Sabha (circa 800km) sections in Libya.